Originally Posted by tiltedbc

Not that I agree with what he did, I have to say most young guys are liable to make mistakes like this given an opportunity. It's sort of build into our biology and it wouldn't take much effort on your roommates part to seduce him.

I'd suggest you sit down with your boyfriend and ask him to decide if he's still loyal to you. If he is, this will be his first and only "mistake" regarding other women. If he can't commit, then find someone new.