Interesting. He obviously wants to do it ttd. I think what you probably need is a coach that will work for him. I struggled for 7 years trying to get good enough to where my partner won't complain about how horrid I was in pretty much every single aspect of dancing. Then I found a teacher that would work for me and dancing has been more fun than ever.
I know it's easy to blame your husband, but a large part of it could be that the coach(es) you're using just don't work for him. I'm not defending him. I'm just saying that it's obvious you still would love for this to work and I think I can confidently say there's still hope for him.
greetings earthling, nice to see you here!