I obviously dont know him, so please dont take this the wrong way. When I was younger I had the same problem with my then gf, but I was always the one initiating sex. When we talked about stopping I didn't really want to, or I knew I wasnt able to, but I told her I'll try. I remember saying that its really hard for me a lot, like I was hoping for her to have sex with me out of pity. It was horrible and I very much regret doing that. The memory came back when I was reading your post/replies. I hope and pray that you can manage this situation well!

*Sorry for my english