These two are getting divorced because he’s a narcissist and she is no longer the trophy he married.

Sex may not be everything but if you’re not having it as much as you want you might as well be friends. I don’t see how this can be a health issue for this long, if he’d ever been different, he’d be the one pestering his doctor about it. If it’s psychological, he had your year- long break to start resolving it to…

This is not a problem that gets better as relationships age. Would he be open to an open relationship? Would you? If you aren’t fine with not having that much sex/knowing someone is only having sex out of obligation, I would cut my losses.