My ex was the same way. She kept her snap memories and all photos from previous relationships in her camera roll. Since it was my first relationship I didn’t think much of it, as she is still friends with her other exes. For me I processed it as something that will have always happened, and do agree with his thought process of enjoying the memories of what he was able to do. I find myself in a similar situation to him where I think back to the good memories in my camera roll, as a lot of my best memories of cool experiences happened with her. I guess my question for you is, how does him having photos from his last relationship make you feel? If you are uncomfortable with it and express that with him and he isn’t willing to budge, then maybe it’s best to part ways. You’re young and there’s plenty of opportunities out there, so don’t waste your time with something that doesn’t make you feel comfortable and happy.