Wondering how to know if your boyfriend or girlfriend is cheating? While there’s no guaranteed way to know without proof, there are clear behavioral, physical, and situational clues that can strongly suggest infidelity. The key is not one sign but consistent patterns that don’t add up.
Though there is no definite way of knowing for sure short of a confession or catching them in the act, there are some ways to know if it’s likely your boyfriend is cheating (or your girlfriend is cheating).
Let’s define cheating first.
What Counts As Cheating In A Relationship?
Cheating is: Someone who is in an exclusive relationship who is also secretly involved in a romantic relationship with another.
So if that is close to your definition as well, then I want to show you how to know if your boyfriend or girlfriend is cheating.
Clues of a Cheating Boyfriend or Girlfriend
I realize that you may be in some degree of fear, frustration or sorrow as you read this article.
For that, I offer my deepest sympathy.
I can, however, offer the following information as a tool for you to use in determining the likelihood of whether or not your significant other is cheating.
It might require some detective work on your part, but you probably agree that knowing if your boyfriend or girlfriend is being unfaithful to you is worth the work.
The strongest clues usually aren’t hidden, they’re changes in behavior you can see without looking for them.
Here we go:
Phone Behavior That Can Signal Cheating
If you already think your boyfriend (or girlfriend) is cheating on you but you want to know how you can know for sure, you should add an item to your list of clues if you notice that they turn off their cell phone when with you or that they leave the room when taking or making calls.
He/she might even become angry if you answer their cell phone or touch it at all.
If you live together or share bills, you could check the cell phone bill for calls made if your plan provides that information.
Often times these calls are in the morning or the evening while they are driving to and from work.
The only good thing about a cell phone bill is that some list all the calls made in a billing cycle (this can be requested of your mobile provider).
Most cheaters consider a cell phone to be a necessity because it allows them to make calls while driving and away from home, but if he or she does not have one, you might want to buy them one just so you can track their calls.
Another detail to examine on a cell phone bill would be extremely long calls.
Sometimes such calls can be for business matters, but if your bf/gf is in a profession that doesn’t require a great deal of phone use, or if their cell phone use has increased for no apparent reason, you have logical reason to be suspicious of cheating if this change is accompanied by other clues as well.
Also take note if you receive an unusual amount of wrong number or hang up calls to your home phone (if you have one) and especially if you notice his or her cell phone ring immediately after someone hung up when you answered the landline.
Another sign of a boyfriend cheating (or a girlfriend cheating) is if they occasionally end the call suddenly when you enter the home or room.
Digital Behavior: What Changes Matter (Without Invading Privacy)
Social Media Signs Of A Cheating Partner
A phone, computer, or tablet can sometimes reveal clues, but not in the way most people think.
You don’t need to spy, install software, or go digging through private accounts to notice meaningful changes. In fact, doing so can damage trust and even create legal problems depending on the situation.
Instead, focus on behavior shifts you can observe naturally.
For example:
- Your partner quickly minimizes screens or switches apps when you walk into the room
- They become unusually protective or defensive about their devices
- Their usage habits suddenly change (late-night activity, increased messaging, or constant notifications)
- They take calls or respond to messages in private when they didn’t before
None of these alone prove cheating.
But when several of them appear together, and they represent a clear change from how your partner used to behave, they can be meaningful.
The key is this:
You’re not looking for proof through spying. You’re looking for patterns that don’t match their normal behavior.
And if something feels off consistently, it usually deserves your attention without crossing lines that could make things worse.
Phone Behavior And Communication Patterns
One of the most common areas where changes show up is in how your partner uses their phone.
If you’re wondering how to know if your boyfriend or girlfriend is cheating, pay attention to what’s different, not just what exists.
Here are some patterns that can raise concern when they represent a shift:
- They leave the room to take calls when they used to talk around you
- They silence or decline calls more often when you’re present
- They become irritated if you casually pick up or look at their phone
- They suddenly keep their phone face down or on them at all times
- Conversations seem to end abruptly when you enter the room
You might also notice:
- Increased frequency of texting or messaging
- More activity at unusual times (early morning or late at night)
It’s important to understand:
A phone itself isn’t the issue, it’s the change in behavior around it.
Trying to monitor, track, or control someone’s phone use usually backfires and damages trust further.
Instead, focus on whether their communication habits have shifted in a way that doesn’t make sense given your relationship.
That’s where the real signal is.
Money And Spending Clues Of Infidelity
High credit card debt and unusual spending could be supportive of the suspicion of cheating.
You need to look for credit card bills containing unusual expenses that may be gifts.
That includes jewelry, travel, cosmetic products, perfume, florist items, items purchased outside of their personal interests (like team jerseys if your suspected cheater is not into sports), and lingerie you’ve never seen.
But if he/she is a smart cheater, they’ll have lots of cash on them without good reason.
You may also notice an increase in gas purchases on the credit card that add up to more miles than they should be driving.
Take note of the daily mileage so you can notice unexplained increases.
Again, be careful that you don’t violate their privacy and that you don’t sound like you’re making an accusation.
If you aren’t a joint user of the card or account, you don’t have a right to comb through it without asking.
That obviously makes things more difficult, but you have other clues to help you.
Physical Changes That May Indicate Cheating
It’s common for a cheating girlfriend or boyfriend to alter their personal appearance to the likes of the lover.
She might get a new hairstyle, visit the tanning bed, change perfume, buy large amounts of new clothes including lingerie and sexy underwear.
He might join a gym, begin or increase taking Viagra without increasing lovemaking sessions with his girlfriend, start wearing a new style of underwear (some she likes or bought for him), shave body hair or begin using a product to color his gray hair or a gel to restyle it.
Though there is nothing inherently wrong with these actions, if they exist along with other clues, you may have a cheater on your hands.
Concern would make sense, but don’t confront your suspected cheater unless the evidence is overwhelming.
Relationship Behavior Changes To Watch For
Suddenly your significant other seems uninterested in your relationship and has fewer conversations with you.
He or she makes spontaneous plans that don’t include you and gives you little time to object.
The cheater may ask specific details about your schedule for no apparent reason.
Sex between the cheater and you may increase or decrease.
He or she may request different kinds of sex or suggest a threesome or swinging.
Often times cheaters do not want to share baths or sleep while embracing their partner.
If that is different, then there might be some cause for concern, but if your partner hasn’t ever wanted to share a bath or sleep while embracing, then it’s not a clue.
Work And Schedule Changes That Raise Red Flags
If your partner comes home later than usual and becomes angry when you ask the reason, there’s probably a problem.
Look for recent hires at work and if they are of the opposite sex, ask your spouse about them.
For example, if there’s a new woman at work, ask him if he thinks she’s pretty.
If he says no but when you meet her she is very pretty, you may have a cheater.
After all, why would he lie about her looks?
The answer could be that he doesn’t want you to be suspicious of her or his relationship with her.
An innocent man in a healthy relationship should be honest.
He might say something like, “She’s pretty, but not as pretty as you,” if you don’t have a track record of punishing him for telling you the truth.
If you’re a man suspecting your girlfriend is cheating, simply switch the details above to your situation.
Signs Someone May Have Been With Another Person At Home
When you get home after the suspected cheater has been there “alone,” look for the following clues to see if he or she has had an encounter with the lover:
- The bed comforter/sheets look as though more than one person has been lying on it and, perhaps, moving around.
- For men suspecting a girlfriend, if the toilet seat is up when you get home, but was down when you left.
- The shower has been used during the day for no apparent reason (possibly to remove perfume, sexual scents or sweat by cheater or lover). If he/she is going away a lot and you suspect an affair is happening during that time, take a casual smell of the person’s hair after they have showered at the house you share and see if their hair smells differently when they return. If it does, it likely means they’ve showered away from home and people in affairs typically shower after having sex with someone else.
- Check the trash locations for condoms. Remember, a smart cheater might not put them in an easily visible trash can.
- Note if the window shades in the room you share were open when you left, but are now closed even though it’s the middle of the day.
Can You Ever Be 100% Sure Someone Is Cheating?
You may find many of the clues in this article and yet your partner MAY still be faithful to you.
This article in no way implies guilt on anyone and may not be used in a court of law or as legal grounds for any charges or demands.
Nothing short of catching your partner in bed with another person will prove beyond a doubt that cheating is taking place, but usually your suspicions are correct.
If you have evidence that your girlfriend or boyfriend is cheating on you, don’t automatically give up on your relationship. I can help relationships that have been hurt by cheating.
You may want to know why a boyfriend or girlfriend cheated and you have every right to want a reason.
But it’s unlikely you’ll receive an honest answer from your partner and no matter the reason, it doesn’t change the fact that they did cheat.
It’s often pointless and even harmful to chase after the reason behind an unfaithful partner.
The reason for cheating is often illogical and is usually emotionally or physically based.
So there’s little application you can use from a potential answer on why someone strayed.
It’s unlikely they even know the reason, if there is one in the first place.
Sometimes it’s simply a lack of commitment to you that was exploited when he/she met someone they found attractive in one way or another.
If you want to save your relationship in spite of a cheating partner, remember that jealousy, though difficult to resist in this situation, is still your enemy on multiple fronts.
Showing jealousy can actually push your partner even more into the arms of the other person (if there is one).
If you have been cheated on, it’s hugely important that you make a choice if you want to stay with the cheater or leave.
If you decide to leave, stop all contact and completely leave that person’s life. That’s true even if you think you might want them back in the future.
Signs of Cheating: Common Questions Answered
What is the most reliable way to tell if someone is cheating?
There is no single reliable sign. The strongest indicator is a consistent pattern of behavior that doesn’t match your partner’s normal habits, especially across communication, schedule, and emotional connection.
Are changes in phone behavior a sign of cheating?
They can be, especially if your partner suddenly becomes secretive, defensive, or changes how they use their phone compared to before.
Do cheaters always act differently in a relationship?
Most people who cheat show some form of behavioral change, whether emotional distance, schedule shifts, or unusual secrecy.
Can social media activity suggest cheating?
It can point to emotional investment elsewhere, particularly if your partner is hiding interactions or behaving differently than they used to online.
Can someone show signs of cheating and still be faithful?
es. Individual signs can have other explanations, which is why it’s important to look for consistent patterns rather than relying on one behavior alone.
Should you rely on one sign to determine if someone is cheating?
No. One sign on its own is rarely meaningful. It’s the combination of multiple changes in behavior that creates a clearer picture.
Why do behavior changes matter more than explanations?
Because explanations can be misleading or incomplete, but consistent changes in behavior are harder to hide and often reflect what’s really happening.
If you’re seeing multiple signs and something doesn’t feel right, don’t ignore it—but don’t react emotionally either.
What you do next matters more than what you’ve discovered.
If your relationship has been damaged by cheating or you’re trying to decide whether to stay or walk away, I can guide you through the next steps so you don’t make things worse.
To get a clear plan and the best chance of turning this situation around, get my Emergency Breakup Kit here:
👉 https://myexbackcoach.com/ebk
–Coach Lee
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