When I met and got talking with my boyfriend, I had a guy I was fucking. No feelings or anything, just casual sex. As of then, I didn’t even know that I will date my boyfriend, thought he just wanted to be friends, but along the line, things got serious and I immediately cut off the guy I was fucking. A few months later, we started dating officially. He found out I was fucking the guy when he and I were still talking and getting to know each other and has been bitter about it, always bringing it up and making it seem like I cheated on him. I still don’t get it.