I take it you don't live together? Why do you not have other, your own friends? It sounds like, despite being together for a couple years, you're still "dating". I would work on my own life and interests of my own and maybe he'll make you a bigger part of his life and maybe you'll continue to drift apart. It sounds like his ex became friends with his friends and they have remained that way; how did you hear about his ex/friends if you do not see them, etc.?