bothered by boyfriend's friendship with a girl he made out with.

My boyfriend and I are recent couples. We've been talking since June and made it official in october. He went to a festival with a group of friends, and made out with one of the girls and had a deep heart to heart talk about their lives later on. He tells and shows me how much he loves me all the time. But I can't help but feel jelous when I think about it because it happened around the time we started talking. Also, they are still pretty good friends and it bothers me because they're always gonna have that history with each other. I don't wanna be jealous but I am. Any advices?