this have been on my mind

So here's the issue I'm having. My bf and I dated a year and broke up from April to June. When we got back together it was official from day one and we decided we would stay together while we started at different colleges. So I moved into college last august and my bf was on vacation with family/friends. He told me about a family friend who was there with her daughter who was the same age as my bf and starting at his college too. My bf talked about her a lot to me on the phone during this time but I thought it was good since he knew no one at his college. Well I come home from break and his parents gush over her. My bf at one point tells me his parents thought they were kissing on the beach and he told me he didn't. Well here I am now a year later and this just bothers me. I never met the girl so idk if she would be that pushy with a guy she just met who has a gf. I feel weird bringing up to my bf but I don't want to let it go if he did. I've been waiting for him to kinda spill secrets to me after we make out  (we sometimes confess like stupid little things lol) what would you do? How do I approach this? I trust him now I just want to know what happened then.