I have been in a LTR with a girl I go to the same college with for about 9 months now. For the most part, it is a good relationship and she respects me and what I say. As with any woman, there are occasional shit/comfort tests that I deal with by holding frame, etc. We have sex regularly and hang out often but not all the time like stereotypical college relationships. I have met her family, who seem like very nice, upper-middle class, decent people. Her older sister has been in an LTR with her boyfriend for over 5 years.

For the past few weeks, she has been on a study abroad trip to Europe that lasts for a total of two months. She's going on a program with her best friend, who's known to hook up with a lot of guys. Since she's been there, she has been drinking a lot, partying until 5am and generally partying a lot more than she usually does at home.

We got in an argument about a week ago which resulted in us not talking for a week. We eventually talked and got through it but the first thing she talked about immediately afterwards was her new best friend "John" and how he cheats on his girlfriend back home. She claims it made her lose all respect for him but also told me this weird story about he kept telling her "how hard it is not to cheat". She also told me this conversation she had with her best friend where they talked about whether she could cheat and they both agreed that she was incapable of doing so. He also appears on her snap stories occasionally and she mentions hanging out with him or random stories about him sometimes.

She was also extremely curious about a situation I told her about where some girl tried to hook up with me but I turned her down.

So automatically this puts red flags in my head, as I've read similar stories online about this exact type of situation. I'm not the type of person to even acknowledge things like this, I'm pretty effective at holding frame. So I haven't asked her about what's going on about her and this dude or accused her of anything. She claims that "he's like her mean older brother who takes care of her", which sounds a lot like that dude is holding frame and dealing with the usual shit tests she gives other guys.

With that said, she has been acting normal and often says she misses me, texts me a lot and snapchats me. It's not like she is trying to make me jealous, this dude just seems to appear a lot.

Now the question is what do I do? I can accuse her of something but if I'm wrong, I put the idea in her mind and she actually does it because it seems like she already likes this guy. On the other hand, if I'm right she will deny it and start fighting with me. It seems like I should just wait until she gets home in order to ask her about it.

I'm not sure if my red flags are warranted or this is some dumb anxiety. This could be some weird trickle truth or my gut over analyzing things.