Quoting The Master:" and if they said they didn't want to go anywhere but its obvious they're miserable?"
I think I would sit down with my SO and have a very frank conversation. I'd explain what he's doing that makes me think he's miserable and let him know that I don't want that for him. I'd tell him he can go, and if that's what he decided he wanted, I'd let him. Because I wouldn't want him to be unhappy, but if he wanted to stick by me through whatever this is, I wouldn't walk away from him because deep down, I wouldn't want him to go either. Life happens, it is not always perfect and it rarely goes how you plan. Sometimes it's messy and sometimes it is downright terrible. It's how you pull each other through the bad days that makes your relationship that much stronger. I would ask him what I
can do to make things better. You may not be able to give him a big family by conventional means, but there are other avenues that you can consider. Adopt, take on foster children, surrogacy. Also, sex is not the be all end all of intimacy. Intimacy is about being close to one another. Share a bubble bath, massage each other, cuddle, make out like your teenagers again. If you can't do penetrative sex but you still want to please him sexually, there are other things you can do for him. I don't know what your health issue is, but discuss ways you can work around it. Is it physically not possible for you to have sex or is it just that you don't feel like it? If you just don't feel like it, why? (You don't have to answer me, I more mean ask yourself.) Once you figure out what that is, ask yourself what he can do to make it easier on you, assuming you want to attempt to get some kind of a sex life back and are willing to try to. And don't misunderstand, I get that this is an illness and that it's not your fault. But don't expect him to hold the relationship together by himself, kwim? Work together to see what you can do to make you BOTH happy.