What does he mean by this?

It sounds like his joke about the 8 month waiting list was a kind way of telling you that it's not appropriate for him to give you his number. I think sometimes it's possible to feel a connection with a guy, and he can feel a connection with you as well, but he still has a real bond with his girlfriend that is stronger than the feelings (if any) he has towards you. He sounds like a great guy, and it sounds like you guys are great friends, but I think that you should focus on remaining friends with him. If he breaks up with his girlfriend sometime down the road, then maybe you can try the romance route, but until then I think you'd be a happier person just dropping it and trying your best not to think of him that way.