I suspect my gf is cheating on me

Basically, last weekend, a guy that works at the same place as my gf asked her out twice. She told me she said no and rejected him and told him that she already had a bf. Or at least that's what she told me. I wasn't actually there when it happened I suspect my gf is cheating on me with that guy because firstly, she's been going on about him yesterday and today and that's just unnecessary. Also, I don't know why she would continue to talk about him. Secondly, she hasn't talked to me tonight and that's very unusual because she never does that and I just can't help but link it to the guy that asked her out twice. This could just be my imagination going wild and me over thinking but I have a bad gut feeling about this situation. Also, the guy that asked her out twice called her princess and said that he could treat her better than I can. Obviously, I was very angry about this. Also, my gf said that she felt bad for the guy when she apparently rejected him and that's a bit weird seeing as he's just some random guy. As I said, it could just be my imagination going wild and me over thinking this but I just have a bad gut feeling about this situation and think that my gf might be cheating on me with that guy. I'm not sure if I should talk to my gf about this or if maybe I should talk to the guy that I think she's cheating on me with. But I don't really want to come across as a jealous and suspicious bf. For all I know, he might be cheating on me with that guy and she might've just lied to me about rejecting him. I need some advice on this situation.

Sit your GF down and have a serious conversation with her regarding her silence and why she talks about the other guy and why she feels bad for him. That way, her answers may or may not back up your gut feeling which is kicking in because there's a problem within your relationship and this guy has basically bought them to the fore. Ask yourself why your GF would even think to talk about this guy aside from mentioning to you about him asking her out....twice.

Hello Anarky, from my POV I can say that your GF is just being honest with you and letting her thoughts out to the person she trusts the most, you. When the guys said the he could treat her better than you, why did you get angry? Is it true? Because I've been on the same situation and I have just said: "how much does he know about how I treat you to have such an opinion?" No anger. Only curiosity. A relationship is a thing of 2 and where the 2 partners have to work everyday to maintain healthy. Another thing is that if the guy works at the same place, is not just a random guy. It might as well be a soon-to-be friend. But the post, it was written by your insecurities. Now, let's say that she's cheating on you. Why would she do such a thing? Why hide it instead of talking openly as she already did with her other thoughts? I think you now that maybe you're not being as good as you could be and that's making you feel insecure about your GF. But then again, that's your problem, not hers. Talk with her in good terms, ask her if he needs you to improve something for the relationship to be better. Don't fight. Colaborate. Good luck!