Welcome to PC!

I'm sure you're not doing anything wrong, but you mentioned that he doesn't want you to touch him because of his weight gain. It sounds like he has low self esteem and body image problems. Have you tried maybe doing a sport or working out together? I would just say, "hey, why don't we go for a walk after dinner?" or "Do you wanna go for a hike or a bike ride this weekend?" Maybe there's an adult sports team in your area you could join together? (My town has co-ed kickball). Even just going to hit around a tennis ball would help. I think these things will help him get active which will help him lose some weight, but they'll also build confidence, which might help out in the bedroom. I wouldn't tell him you want to do these things with him cause you want him to lose weight, just spin it as something fun the two of you could do together.

Good luck!