Frustrating..

I don't want to be a pain in the ass and just keep bringing it up. But my boyfriend and his baby mama still haven't gotten their divorce. They've been separated for 3-4 years. She cheated and left him for the guy she cheated on him with and has now a 1 year old with the guy. And it just gets me upset that he's still waiting idk what though. And I've said to him she wouldn't take his daughter away from him I can tell just by how she talks about he will do anything for his daughter. But he will always say it's cause he's afraid she will take her away from him. I know he loves me or else he wouldn't be with me. But I think to myself how can you talk a future with me if you are stil stuck in your past, am I right or what? Should I ask him another time? It's been two years of me asking..