A friend of mine (we're not especially close but have spent a lot of time together) has a boyfriend who she has been with for over 2 years now. He cheated on every one of his ex girlfriends. My friend started her year abroad in September and she was a bit worried about him being apart but they seemed to be doing okay.
I was told by my ex boyfriend (who is living with her boyfriend) that the boyfriend has cheated. He cheated on her at a party and was seen by others, who all are friends of the girl too. None of them have told her and I feel absolutely awful for her.
I want to tell her because I think it is so wrong not to, but also I don't really know what to do.