Infidelity: how to tell if your partner is being unfaithful

Unfaithful partners. Just the phrase is enough to make some people angry, others sad and even more just nervous. This can be a devastating blow. Nobody wants to be with a partner that also has other love interests, it’s often thought of as the ultimate betrayal. With the modern world providing advances in technology and more opportunity than ever how can you know if your loved one is trustworthy?

As Private Investigators this is one of the many services we offer and is one of the most frequently asked questions, when people call us for help and advice. Insight Investigations offers a wide range of services on relationship investigations to help people get to the truth. Speaking with one of our experienced male or female investigators can help determine the best course of action to give you piece of mind.

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When you look at the numbers it’s hardly surprising that we are distrustful of each other. In a survey conducted by Truth About Deception, which currently has over 90,000 respondents, over 50% of women admit to having a one night stand. Men over 75% admitting the same thing.

Surprisingly, over 50% of women and 70% of men admitted to being unfaithful to their partner more than once. It’s no wonder relationships fail with figures like this on infidelity.

Private investigation following the target and taking images in public places

But how can you tell if your partner is being unfaithful?

There are hundreds of guides already out there which can tell you the signs to look for. Anything from the old-fashioned lipstick on the collar to working late has already been covered, but most of these have been written by people with no concept of the online space in which we now live.

Today, people immerse themselves in social platforms online and setting up and maintaining a relationship has never been easier. So how can you check on your partner and more importantly, is it different for men and women? What makes them stand out as being unfaithful?

Sure, some of the signals that your partner is being unfaithful on you are consistent across the sexes, but there are some very subtle differences and things to watch out for.

The following list is as up to date as we can make it and each of the items mentioned here has been a sign in one or more of the cases of unfaithful partners that we have investigated. It’s worth saying though that the presence of one or more of these signs does NOT mean that your partner is definitely being unfaithful.

If you find more than five of these though then you might need to do some more digging.

  • More secretive with phone and social media
  • Change in personal grooming
  • Feeling not quite right and changes in mood and behaviour
  • More distant with less physical contact
  • Increased work patterns or new hobby/reason to leave the house

Here is the 2021 modern list of signs that your man or woman could be being unfaithful.

Jump to 20 Signs your woman is being unfaithful

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20 Signs your man is being unfaithful

Two phones

This is a dead giveaway. Who needs two phones these days? Sure, you still get those who claim they need one for work and one for personal use and it is true. There are some companies who still refuse to allow people to use their work phone for personal reasons, or you may actually want to separate your work and personal life, but in most cases, two phones are not a requirement.

If you do separate your life like this then your work phone may not be necessary on holiday so bringing two phones could be a giveaway.

Today you can have multiple personas on Twitter and many other social platforms on just one phone, so unless there is a genuine reason for having another phone, take this as a signal.

Phone on silent

The thing about modern technology is that it can have a nasty habit of intruding into your life when it’s not wanted. Take for example a text from someone you are having an affair with. Not only does it ‘ping’ when the text arrives but it also stays visible on the screen even if you have your phone locked. That that can be very inconvenient if your partner happens to look at your phone.

Setting the phone to silent reduces the risk of your partner being aware of the text in the first place, so we include it in the list of possible signs.

Secretly texting in the middle of the night while your partner sleeps while your phone is on silent. Coincidance?

Different ringtone or text tone

Many of the older generation (and by that, we mean anyone who owned and NEC P3, or Nokia 3210) never change their ringtone. In fact, most people over a certain age either don’t want to or don’t know how to change their ringtone.

Contrast that with the younger users and according to one online survey, only 15% leave the factory defaults in place.

Changing ringtones or text tones can mean that you know automatically when someone is ringing or texting you and that can be a godsend when you are trying to separate parts of your life.

If your partner has more than one ringtone or text tone then if might be a sign.

Sudden interest in personal grooming

Individuals personal grooming or hygiene habits, may change once in a long-term relationship.

Contrast this with having an affair and suddenly people become more fastidious about their personal grooming and will go to great lengths to look presentable.

More time spent in the bathroom or a sudden interest in grooming products could easily be a sign.

Appears more secretive, particularly with their mobile phone

Whilst technology allows far more ways to have an affair with people, it does require one thing that you can’t hide and that is time. It takes time to text or call someone. It takes time to send photos on Snapchat. It takes time to flirt.

If you are in a relationship, finding the time to do this when your partner isn’t looking can be tricky.

If you find that their normal routine is somehow different, especially in the evenings, then this could be a sign they are taking the time to flirt online. Signs, like taking their phone out with them when they normally wouldn’t, or even taking it to the shower or toilet, can simply be them finding time to contact someone.

More distant, less frequent physical contact

When a partner decides they want to move on, they want to move on. Sometimes this manifests with becoming more aggressive, accusing their partner of infidelity to hide their own indiscretion or generally changing their behaviour to force the party to confront the situation.

In these circumstances, they will want to spend less time with you, will be resentful of having to be around you and won’t show the same degree of affection that they once did.

A diminishing of affection is not, in itself a sign, after all, when people have been together for years this can be a natural occurrence. But add it to the other signs here and it could be a signal.

Infrequent love making

If they are finding excuses to avoid intimate contact with you the this could be a sign that things are not right.

Nights out with ‘friends’

Generally people love to go out; it’s in their DNA to meet and bond with friends. There’s nothing wrong with this unless it becomes more frequent than it once was.

Sudden urges to unexpectedly meet with friends for a “quick pint” a or “quick catch-up” or coming home late after stopping out with their friends.

There are legitimate reasons for men to do this and there are times in their lives when a new group or crowd will mean they are out more often.

Ultimately if you find yourself sat at home and have no ideas where they are or what they are doing then this could be a sign.

Especially if when they return home, instead of being nice to you to make up for all the time they spent away they turn on you and make out that you are somehow trying to control them, the alarm bells should ring.

Unusual shower times – late at night

People can be creatures of habit. They do the same things at the same times most days. Most men will shower either morning or evening and the same with shaving.

If they suddenly feel the urge to shower more frequently or change the time when they are showering and shaving you might need to ask the reason why.

Sudden interest in loading the washing machine

Despite years of gender equality, there is no doubt that in most households, laundry, cleaning and ironing are handled by the woman. In most cases it’s not a deliberately sexist thing, it’s just the way it happens.

So if your partner suddenly starts to show an interest in loading the washing machine, this should be considered a sign.

Why, when they NEVER do it, should they suddenly be concerned about the state of the laundry? Closer inspection might reveal tell-tale signs and smells on his clothing that he rather you didn’t notice.

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Working later for no apparent reason

A classic sign. Sometimes, in fact, quite often, this is not an excuse for meeting someone else. In fact quite the opposite; it’s an excuse for not spending time with you.

The extra half hour or hour at work could be all they need to text or chat to the person they are having an affair with but from their point of view, it’s another half hour or hour when they are not with you and when you can’t accuse them of having an affair.


Much underrated, smell is actually a classic tell-tale sign.

Everyone has a smell. Researchers have known this for some time and companies have peddled the magic’ pheromone’ scents for years, despite the lack of evidence that they actually do anything.

A 2016 report however in Psychology Today, shed some more light on this subject. Their research suggested that women can detect genetic compatibility by smell (but men can’t) and with nostrils that sensitive then they are very likely to notice a change in a man’s smell.

Men smell differently when they have been with a woman who wears a different perfume to you and they definitely smell different when they have spent some time having sex with them.

So, as well as keeping your eyes and ears open, next time keep your nose alert for tell-tale changes in your man’s smell.

Social Media

Ubiquitous in modern life, most people have some form of a social media profile.

Facebook, Twitter, Instagram, Snapchat; they can all tell a story if you look hard enough.

As a Private Investigator, this is one of the easiest and most obvious things to check. Although it is unlikely that your partner is going to post pictures of their infidelity on social media (although it has happened!) it can give some interesting clues to follow up.

Take a look at their images they are posting, do you know where they are and who they are with? Are there any new faces you haven’t seen before? What about the locations? Do you recognize where they are and who they are with?

Text messages folder is empty.

Who deletes their text messages? Most of the time men can’t be bothered, unless of course, it’s impinging on the phone’s memory in which case a clean out is a priority!

Most men simply don’t delete texts and as such, if you can see their phone then you can see their life played out in all its dull detail.

It’s a rare man who has a completely empty text message folder. At the very least there is probably a text in there which announced the birth weight and name of one of his friend’s kids. And most men keep these because they are notoriously bad at remembering this sort of detail.

An empty text message folder might be a sign.

Passwords and logins have changed

If you used to be able to get into your partners phone, computer, tablet or other device and suddenly you find you can’t then you might need to start asking why.

And if your partner is spending more time with just one of the devices, more than might be considered usual, then this could be a sure sign.

They have less money than usual

Often overlooked, a lack of funds can be a signal that something has changed. If your partner is one who always has money on them or has the ability to take money out of the bank when they want, then suddenly announcing that they have no cash might raise a few questions.

Now it could be (and we did find this in one case) that a husband had been putting money aside for over a year just to pay for a surprise holiday for his wife. Often, however, this is NOT the case.

Quite often at the start of a new relationship, there will be a display of affection and this often manifests itself in the form of gifts. Whilst his new girlfriend may be able to hide a pair of diamond earrings or a necklace from their partner (assuming both parties are in a relationship) hiding the absence of funds in the bank account is a lot harder.

You don’t see any of the bank statements

Leading on from the point above, if you have a joint account and are used to being able to access that account and see the statements, the sudden absence of statements in the house might be a signal.

Banks make it easy these days to switch off paper statements but this can often leave the other partner in the dark.

Details like where and when cash has been withdrawn from cash points can be an indicator, especially if they were not supposed to be there at that time.

Location services are switched off

Most mobile phones these days are equipped with some form of Geo-location device and unless you specify otherwise in settings, often it is enabled by default.

Men, being tech savvy in the main, are very adept at switching this off.

Given that pretty much all the apps these days require it switched on to work properly (think Facebook or any of the Map apps as an example) then when it is switched off you need to ask why.

Unfaithful partner will turn off their location services so that they don't give away where they have been

The browser history is regularly deleted, or private browsing is the default

Internet browsers by default always keep a history of which websites you have visited. 90% of people never consider this and as such, they never delete their browsing history.

An empty browsing history should be a sign for concern.

Similarly, most browsers allow you to surf in private so if your partner has spent hours on the computer, but when you check the browsing history it shows nothing, then there is something that is being hidden.

You ‘feel ‘that something is not quite right

Often underrated and regularly ignored in the early stages of an affair, the good old fashioned ‘gut feeling’ is usually right.

Trust your gut instincts and if something feels wrong, it probably is.

Jump to 20 Signs your man is being unfaithful

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20 Signs your woman is being unfaithful

Using social Apps that you don’t use

If you are a tech savvy man you probably have lots of apps on your phone. But if you suddenly find that your partner has social media apps she’s using that you are not using yourself, this could be a sign she’s keeping her communication secret.

After all, if you haven’t got the app and you’re not friends with her on it then you simply can’t see who her friends are, can you?

Her phone is locked

You’ve previously had access to her phone or at least you’ve known the code for opening it. Most couples know this about their partner as a lot of the codes are simple and often reused across other devices.

Suddenly you find her password has changed on phone and access to other things that you previously could see has also been restricted. It could be just that she is security conscious and following best practice guidelines for changing passwords on a regular basis. Or not.

There’s a change in predictable behaviour.

When couples are in a relationship they develop routines which even if not immediately obvious to the rest of us, are there nonetheless. As a partner you know these routines and if there’s a sudden change or even a more subtle change over the course of a couple of weeks, this could be a sign.

Their Phone bill shows more calls and messages to a certain number

Mobile phone bills can be a great source of information; if you can get to them. These days most of them are hidden online with password protection.

If you can see them then a quick sign is an increase in the monthly cost. If people pay more than the standard tariff each month it is often because more pictures are being sent. A new relationship is often a time when this sort of thing happens.

Mood changes; for better or worse

Women are generally much better at hiding their feelings than men but they are also more likely to share them with friends. Whilst men clam up and (unless they are bragging) don’t tell their friends, women are more comfortable sharing the news with a close friend.

Whatever the woman’s feelings, however, it’s hard to hide that from a partner.

If she’s happy she won’t be able to help herself and this will be evident in her manner, comments and general demeanour. If she’s angry however it is equally evident as any partner on the wrong end of this will probably attest.

If a woman is having an affair then happiness might be the order of the day (assuming she’s enjoying it) but equally a heightened sense of annoyance with her partner could be a sign that she is having an affair. Or that she’s just annoyed with you. Remember, not every one of these is a sure-fire sign.

Change in weight or appearance and going to the gym more

Women commit infidelity in very different ways. Men tend to simply take the opportunity when it arises whereas women as more selective. They typically look for someone ‘better’ than their partner, or as it has been described, “Women are more likely to cheat up, while men are more likely to cheat around.”

This explains why a woman who is having an affair will often take more interest in her physical appearance and lose some weight, change the way they look or start attending a gym more often.

With a massive 75% of women saying that they have been unfaithful because they were having problems in their relationships a change in appearance when coupled with other signs could be a key indicator.

Change in musical tastes

We all tend to like the music we like and this doesn’t change very often. Sure, there are new bands that come and go and our musical tastes can vary but if you are into classical music you are hardly likely to start listing to AC/DC.

Back in the old days, when you started a relationship with someone you made them a compilation tape. How many women now have that cassette sitting in a drawer somewhere?

The sudden appearance of blank CD’s with tracks you don’t recognize on them, or a data stick with some new bands on, could be a signal that someone is sharing their love of that music.

Being vague on things, like ‘I can’t remember?’

Men often crumble under pressure. Given an inquisition by their partner, they find themselves unable to lie and blurt out the truth, or at least a very bad lie.

Women, on the other hand, seem quite adept at dodging the issue. Under pressure, they are more than likely to claim no knowledge of the time, place, situation or person in question.

Unless they normally suffer from a poor memory then an inability to recall events and people might be a sign that they do actually remember it but are choosing not to share that information with you.

A pronounced need for privacy

Everyone needs a bit of privacy, but when you are in a relationship you open up and let your partner into your life. Secrets may still exist but not as many as before; after all, if this person is your ‘best friend then surely you would share stuff with them?

A sudden desire for more ‘me’ time or the need to be alone is often a sign that the woman is shutting the man out of her life and this can be a sign that something is going on.

A change in sexual intercourse frequency

Possibly one of the most common signs, there is a change in the frequency of intercourse.

Contrary to common belief this doesn’t necessarily mean a reduction; sometimes it can be an increase. After all, what better way to hide infidelity than by having more frequent sex? Most partners on the receiving end of this would be grateful for the opportunity and therefore be unlikely to complain. But it could simply be a way of hiding an increase in a woman’s libido because of flirting, or more, with a new partner.

You can’t see her bills

Much like men and their phone bills and bank statements, women are also adept at hiding changes in their financial position from their partner.

If you could see her phone bill before and bank statements but these suddenly aren’t obvious or available this could be a sign. Much like men, women having an affair will be going places, spending money and making calls that they rather their partner didn’t know about.

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Talking a lot about her new ‘friend’ at work

Like it or not, many relationships start in the workplace. This is logical because in today’s modern environment you are more likely to meet and spend time with someone in the workplace than almost anywhere else.

Spending time with the person they are attracted to at work isn’t in itself a problem, but most men have no ideas if a woman has an interest in someone or not.

One sign could be that she may discuss a co-worker more and how they are good at what they do, how funny they are and how this affects life in the office.

Turning phone location on and off frequently.

Men aren’t the only ones to be tech savvy. Most millennial’s have grown up with the technology and unlike their parents, they know how to use devices in the digital world.

We have seen very tech astute women who simply disable location services when they visit their lover and then re-enable it when they are back in a location which would be regarded as ‘normal’. Were it not for close surveillance it would have been hard to prove where they had been.

Most people have no need or desire to frequently turn on and off the location services on their phone. If your woman is doing so then this could be a sign.

Matching underwear

Much as men can be unkempt in appearance when they are in a relationship, women can also relax their behaviour when they are part of a couple.

One of the signs is matching underwear. At the start of a relationship, most women will make an effort to ensure that bra and knickers both match and are feminine and attractive. Once in a relationship, this can change to just making sure that they don’t show through the clothing they are wearing.

If your woman regularly puts on different coloured bra and knickers (the comfortable ones) but suddenly changes this to wear matching sets it may well be because they expect someone else to see them wearing it.

She says your suspicions are nonsense

If a man is forward enough to confront their partner with his suspicions, it is likely to go a number of ways.  Statistically, women are twice as likely as men to think that their partner suspected them of being unfaithful and in almost half of the cases of infidelity their partner found out the truth.

When confronted, a woman may simply confess (as this brings the whole thing to a head), flatly deny it or quite often, tell you that you are jealous and or crazy to think that she may be having an affair.

Ironically, in this case, a denial isn’t quite a denial. If it is turned around to accuse the man of being stupid or paranoid it can sometimes be a sign that it really is going on.

Oblivious to the fact her partner has made an effort

Men quite often simply forget to make an effort. It sometimes seems hardwired into their DNA. Once all the thrill of the initial chase has gone it can be all too easy to drop back into a routine.

When a relationship is vulnerable though a woman may have her eyes elsewhere and despite a man’s ‘best’ efforts, nothing he says or does may be good enough.

If a woman is ignoring a man’s efforts and seems more preoccupied with her social media account or texting her friends, then this can be a sign that she’s having an affair.

Happy to show you her phone and social media accounts

It sounds counter intuitive but a sudden willingness to show you her email accounts or social media accounts or mobile phone could be a signal.

We investigated a case where this had become the norm and the reason, it turned out, was because the partner was having an affair. What they did though was to clear their phone down on a daily basis so there was nothing untoward to find on their phone.

They came unstuck though when on holiday and their partner checked their phone at a time when normally they would be at work.

Unfaithful partner social media secret messages

They ‘like’ someone’s posts more than others

Astonishingly, according to an online survey, 54% of women have had a one-night stand and 45% of those affairs were with someone their partner knows.

Of course, it makes sense; you meet people as part of a social group, spend time with them and can become attracted to them. Quite often, therefore, an affair tends to be with someone you know or someone who is associated with the same groups of friends or work colleagues.

And as you are all friends there is no reason that you should all be linked on the same social media platforms.

If you look closely, however, you may start to spot a pattern. A woman may be subtly ‘liking’ posts from a particular person more frequently than others. This is not of course, in itself a sign of infidelity, but it can be a signal that they like that person slightly more than you would expect.

They may post quotes online or refer to things which are out of the normal.

Erratic or unusual behaviour is often quoted as one of the classic signs that someone is having an affair.

These days that can manifest itself solely in the digital environment, with everything else seemingly unchanged.

We have seen cases where women started to post unusual quotes or out of character comments online which were, it turned out, completely at odds with her day to day life. To all her friends and family everything seemed normal but the nature and frequency of her posts online betrayed a mental turmoil about the relationship she found herself in and the fact that she was having an affair was causing her to seek release online.

Constantly keeping tabs on her partner.

How many times a day is it normal to keep tabs on your partner’s movements?

Most couples ‘check in’ with each other a few times a day and with so many ways to keep engaged in the digital world it’s quite easy to do this.

In one case we investigated a woman was keeping tabs on her husband up to twenty times a day. Constant texts or phone calls from her were dressed up as being friendly but the reality, as betrayed by the phone calls, was more often than not, she was looking to find out where her husband was.

The irony in this was that this behaviour was so she knew exactly where he was and therefore when it would be safe for her to meet with her lover and have the affair.

If a woman needs to keep a very close eye on you all day every day, perhaps you should ask why?

Emoticons on posts

We all use them in our posts but what does an emoticon really say about you? This post lists ten of the most used emojis by women and what they mean when she is flirting with a man.

If your partner starts to use these in her texts or even posts them on social media platforms you might want to ask her some straight questions about their meaning.

Of course, this is not an exhaustive list. It’s a list of the signs that we have seen as part of undercover private investigations we have undertaken in the past few years.

The key to all of these investigations that form part of this article is that the signs of infidelity and the reason the unfaithful partner was exposed was often down to their digital footprint.

Wherever you go and whatever you do, modern life finds a way to track your every move.

If you think that your partner may be having an affair and need some help then offer a professional, discreet service. Contact us in complete confidence on the number below or use our contact form and speak to one of our expert team.

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