I do not currently live with my boyfriend since I care for a family member. We've been in a relationship for almost a year, he refers to me as his partner and has committed to long term plans with me. I feel like this is important context, it is a serious relationship. He moved in a college friend going through a rough time to give her a safe place to live and to help cover bills. I was wary of her at first because I've been burned before, but I also don't want to be the crazy paranoid girlfriend. Once I got to know her I realized she was nice and we shared similar interests.
My boyfriend's roommate and I went out for a smoke last night and she told me that about a month or so ago he gave her oral. Then a separate time he had sex with her. And they've cuddled on the couch naked/semi naked before.
I don't know if I should believe her. She seemed quite guilty and was very apologetic, she even offered to let me hit her. (I didn't, but it was a nice offer)
In my head there's 3 plausible scenarios
1. She's telling the truth
2. She's lying for the hell of it
3. She's lying because she wants to date him
Not sure if I should believe it, nor am I sure if I should confront him.