My boyfriend and I have been together for just over three months and almost everyday that I'm with him (more or less 5 days a week) he brings up and talks about someone he's slept with/been with, even during sex a couple days ago. It's starting to hurt a lot and it's making me upset as I really don't want to know about anyone he's previously been with, and he knows this and he always feels bad after he says it when he sees that I'm upset. I've tried to talk to him about it, even a close friend of his has, but I still don't think he gets it considering he still does it... Any advice?