Wow, jacket, our situations are similar. You've been facing all this for so long. It seems like you're handling this all quite well and DB well. Congratulate yourself on that because it's not easy, as we've all learned.
I'm not a vet and can't claim profound insight into your situation but when someone is looking for a romantic spark and feeling unfulfilled in that area, they seek it. I say this because I'm concerned about his friend with whom he is hiking and taking salsa lessons. IMO, you don't take salsa lessons with a female buddy. Then there's his longing for the girl from 9th grade. He's looking to fill some holes in his life. I'm hoping he hasn't strayed officially but to me he's on the cusp of that.
I'll let a vet weigh in because, like my h, your h seems resigned to leaving no matter what changes. It's indicative of a lot of pain, I believe, but some of that pain you had nothing to do with.
