Pathofthorns, you talk with him by being general in your direction of conversation.
My guess is that he is just very comfortable dating
Would you possibly move to be with him (or vice versa) without being married? Since I imagine you are done having children, you might have a lot of leverage if you are okay with the idea of cohabitating without a marriage certificate. Just something to think about. He says he sees you being together forever... Well that's a great sign but if you really are serious about one another you should be able to talk about what you're looking for, especially after two years of being together!
"Hey, you know how you want to be together forever? Well I would really like that too. How are we going to make that work with the distance? Is one of us going to move? Do you see yourself ever getting married again?"
Did you two have any conversations about that in the past, when you were first getting to know each other? Its a difficult subject, but if it is important to you, then you have every right to bring it up, and if you don;t talk about it, it will only weigh on your mind more and more.
When SO and I started getting serious, he told me he was not interested in ever getting married again. Okay, fine, I can respect that, but I told him I beleived in marriage (even after my lying cheating ex) and I would never live with anyone without being married. So we know where each stood from the beginning, and at this point we are waiting for his divorce to finalize and then we will move forward, in some form. What that will be, I don;t know.