Thanks for all the replies. I am surprised to see this is so common...I understand it a little more when kids are involved, but I really relate to your story YouAreHere. That's how she seems...surprised he doesn't want to keep just tiny bits of their life and why that would bother him.
He cares for her too, reasons I don't want to get into personal to them. I think that's part of the reason he stays, to watch over her.
In answer to an earlier question, hes doing ok. I think in large part because ive kind of become his "primary" (this involved a lot of convo with my own spouse). He would get so upset for a while, but now seems to accepting it. I still hate to see him stay...struggle with it every day. but that's his choice.