Do you happen to know how long he tends to wait before getting into a new relationship after breaking up with a previous girlfriend?

It’s definitely possible that he’s not over them if he keeps talking about them, and I think sometimes people can think they’re over their exes but they’re actually not… but it’s also possible that he’s simply talking about his past, which they are a part of, so he mentions them because he was doing whatever past thing and they were there, too. If he’s not giving himself very much time between relationships, though, he’s not giving himself any time to heal and is just jumping from one distraction to another.

I like Anita’s advice to make sure that he’s also treating you well, and I, too, think you should mention that it’s starting to bother you when he talks about them and ask him to be mindful of that. I definitely would see red flags if I had a boyfriend who was talking about his exes a lot. I think just about anyone would.