Finding out that your girlfriend is cheating on you is a real kick in the nards. It’s even more devastating when you discover that the other guy happens to be your best friend. As despicable as it is for your best friend and girlfriend to do this; it happens more often than you think. Sometimes these dalliances go on for a while with nobody knowing about it. The thing is that, in most cases, they are eventually discovered. We’ve probably all heard tales of some dude that caught his girlfriend in the act with his best friend. How crushing. There is no speculation or guesswork. That guy knows exactly what’s going on.

Other times it isn’t so cut and dry. You might have the sense that there’s some monkey business happening between your girlfriend and best friend but you can’t prove it. All you can really do is monitor the situation and fret. You need to be able to analyze things carefully and look for clues. Oh, there are plenty of clues that can be found if you just pay attention. Make sure you have your evidence in order if you are going to start leveling accusations because it is a pretty serious matter and there is a lot at stake. Here are 15 signs she just cheated on you with your best friend.

15. She’s Late Coming Home and Neither will Answer their Phones

Just because she’s two hours late doesn’t mean that she’s cheating and just because your friend won’t answer his phone doesn’t mean he’s with her. When you put the two together, especially if you have that uneasy gut feeling, your mind can’t help but think about the possibility. It makes perfect sense that neither will answer their phones if they are getting busy with each other. It also makes sense that they would both avoid your calls if they had feelings of guilt and didn’t want to talk to you. You should consider that your girlfriend is stuck in traffic with music blaring and doesn’t hear the phone. Maybe your friend is on a date with someone who isn’t your girlfriend and he doesn’t want to be interrupted in the middle of a conversation.

14. She Has His Shirt on When She Comes Home

Now, this one should raise the eyebrows of even the most dim-witted and overly trusting guy. She arrives home wearing your best friend’s old Denver Broncos Super Bowl XXXIII Champions t-shirt. This might not merely be a sign that she is canoodling with him; it could also be a pretty clear message that she wants to get caught. If she fumbles for an answer when you ask her about it then there is something clearly amiss. There aren’t too many good reasons why she would be wearing that shirt but there is always the remote possibility that she comes up with a logical explanation. You probably want to call your friend and casually ask him why she’s wearing his shirt. Maybe their stories jive. Of course, if they don’t then it’s troubling.

13. Her Cell Phone Shows Repeated Calls to His Number

If you have the feeling that she’s been cheating on you then you are probably grinding at the bit to get your hands on her cell phone to see if there is any evidence. Wait for her to hop into the shower or for her to go to sleep then have a quick look. Most women would likely erase incriminating call logs off of their phones but you never know. If you see that there have been several calls dialed to or received from your friend’s number, then you have every reason to be concerned. Yes, it might be something completely innocent like the two of them planning a surprise birthday party for you but if your birthday was two months ago and the calls are more recent then that’s probably not the case.

12. Her Schedule Suddenly Gets Busier. So Does His.

She used to have the occasional 2-hour meeting after work but these meetings are becoming more frequent. Not only that, she’s now participating in Zumba twice a week and she just enrolled in swimming classes. As for your best friend, he’s been putting in a lot of overtime at the office and is taking tennis lessons that coincide with your girlfriend’s swimming classes. Neither of them appear to have any time to spend with you as has been the norm for years. That’s a bit of a head-scratcher and should raise some red flags in your mind. It’s not too difficult to confirm their alibis and if they are both lying to you then they are most likely hiding something. You will want to put the investigation into high-gear and find out what’s really going on.

11. Both Get Nervous when you Mention the Other’s Name

Let’s say you are having a conversation with your girlfriend in which you start referencing your best friend. Suddenly, there is a subtle change in the mood. She avoids direct eye contact with you, starts to stumble over her words, and does her best to change the subject. That’s a little odd. Now, let’s say you are with your best friend watching Monday Night Football at the sports bar over a couple of beers and some hot wings. You casually tell your friend that your girlfriend has been acting a little strange lately and you think she’s cheating on you. Your friend breaks eye contact and desperately tries to change the topic. That’s quite out of character. Your best friend usually offers support and a caring ear. Alarm bells should be sounding.

10. She’s Never in the Mood and He’s Bragging about How Much Action He’s Getting

You’ve tried to wine her. You’ve tried to dine her. You even took her to an expensive romantic getaway last weekend, yet, she still doesn’t seem interested in being intimate with you. There are many innocent and understandable reasons for this frustrating situation to happen, such as depression and fatigue but there is also the distinct possibility that she’s being unfaithful. Perhaps she’s getting her lovin’ from someone else? It’s something to consider especially if your friend has been telling people that he’s been getting loads of action from an unknown paramour. This could very well all be legit. Maybe she’s been working hard for a promotion or there could be an enormous amount of stress due to other issues. Just be aware that such a dramatic change in your usual love-making habits is one of the classic signs that she’s fooling around.

9. She’s Trying to Start Arguments

Every couple in the world has their disagreements. It’s perfectly normal. However, if your girlfriend has become overly hostile and appears to be looking to start arguments on an ongoing basis then there is something terribly wrong. Many people who are cheating on their significant other will actually accuse their partner of cheating. This nasty bit of misdirection is usually effective in turning the tables to focus on your failings. You’ve gotta love mind games and guilt trips!! This devilish ploy puts you on the defensive and can easily be the precursor to a huge spat which is exactly what she could be aiming for. A big blow-out would allow her to justify leaving the house for a few hours to cool off…or warm up with your best friend.

8. They Both Disappear and Return Together

So, you’re at a party with your girlfriend and your best friend is there too. They’ve been acting a little too friendly to each other for your comfort but everyone is feeling a bit tipsy and you don’t want to get too paranoid. Everyone is just having good, clean fun. After a while and a couple more strawberry daiquiris, you notice that your girlfriend and your best friend are nowhere to be seen. A short while later the both return to the party and explain that they were just outside talking. However, now they are a lot less flirty with each other than when you saw them last. He keeps his distance from you and may even leave the party while your girlfriend’s mood has cooled off. It was either a heavy conversation or some heavy petting.

7. You Don’t Understand Her. But He Does.

It must be a horrible feeling to know or even suspect that your best friend has betrayed you by sleeping with your girlfriend. In some cases, the girl shows no outward signs and the guy thinks everything is fine. Then, an innocuous conversation with your best friend ends up being a revelation. He tells you that your girlfriend is unhappy with a certain aspect of your relationship and that you don’t seem to understand her needs. Huh? How the heck does he know? Well, he tells you that they have discussed this issue a few times recently. Huh? Yes, she’s been crying on his shoulders for a while now without your knowledge. He might deny and even act offended when you ask the big question but you need to start thinking about the possibility that you’ve been betrayed by both of them.

6. She Wants You to Spend Time with New Friends

This one is pretty transparent but love is blind and some guys aren’t all that detail oriented. Suppose you met a group of guys that have invited you to a weekly poker game. Your girlfriend finds out about this and keenly urges you to go. “Meet new people. Have some fun. I’ll just go over to Susan’s place and watch Keeping Up With The Kardashians.” she tells you. “You shouldn’t spend all your time hanging out with (insert best friend’s name here).” she continues. She hasn’t shown so much emotion in weeks. You decide to go but it is hard to concentrate on the cards when you feel that she is trying to drive a wedge between you and your friend while conveniently finding herself with some free time thanks to you. She usually hates it when you go out with the boys. Something’s up.

5. Evidence on Social Media

It shouldn’t be surprising that some cheaters get caught when they leave their social media accounts logged in by accident. It has happened countless times and several similar stories are all over the internet. The scenario is pretty much the same. A guy sits down at his computer and finds his girlfriend’s Facebook or other social media account is still logged in. Curiosity can be overpowering so he naturally checks out some of the conversations in her chat. He isn’t impressed with what he finds. Revealing chat sessions are really the only evidence you need to be sure that your girlfriend just cheated on you with your best friend. Text logs on cell phones are just as telling. It’s not the nicest way to find out and it’s even worse if there are multiple guys involved with her.

4. She Ignores Her Cell Phone

This is definitely a sign that something fishy is going on. If her phone starts to ring when you’re around and she doesn’t answer it then you need to ask yourself why. You should also ask her. This goes for incoming texts as well. It is doubly suspicious when she acts frazzled and nervous when it happens and if you add in the fact that she takes her phone into the bathroom with her for a few minutes and you can’t help but be a bit suspicious. You could find that your buddy does the same thing when you’re around. Unless you can see the incoming caller ID then there’s not much you can do but if both happen then it is a sign that she just cheated on you with your best friend.

3. Video or Voice Recordings

You don’t have to be James Bond to get your hands on some pretty decent and cheap spy equipment these days. Some poor guy came home early from work one day to find his girlfriend and best friend on the couch. They quickly moved to opposite sides and appeared startled. The three engaged in a bit of small talk before the guy remembered that he forgot to get milk on the way home. He announced that he would be back in a few minutes and departed leaving his girlfriend and best friend on the couch. He also left his cell phone behind with the voice recorder on. He returned and, later that evening, he listened to the recorded audio. While he went to the store, his friend and girlfriend could clearly be heard discussing the “close call” and that they would no longer meet at the house while he was at work.

2. Your Friends are Acting Strange

You might not know for sure that your girlfriend is getting it on with your best friend but there is a chance that some of your other friends do. This is an uncomfortable situation for all involved and you can sometimes feel the tension in the air. You could find yourself hanging out at a summer backyard barbecue with your girlfriend, best friend, and the rest of your social group. Instead of enjoying laughs in a relaxed atmosphere, your friends seem uneasy in your presence. They also appear to be different around your girlfriend and best friend. You would hope that one of your other friends would enlighten you but that’s not always easy. If this type of thing continues, you might have to consider that she’s been cheating on you with your best friend.

1. You Catch them Both in a Lie

You told your girlfriend that you were going to chill out on Saturday afternoon and watch a baseball game. Your girlfriend had made plans to go out for lunch with a friend from work. So, you called your best friend and told him that the girlfriend was gone for the day and you asked if he would like to come over to watch the game over a few beers. He told you that he was busy painting his bathroom. You don’t think much of it until you check your Facebook page between innings and see them both tagged in a picture that was just taken in the lounge at the Holiday Inn. You don’t need a calculator to figure out this math. It’s a flashing sign that she just cheated on you with your best friend.