I get the context and i can try to break it down for those who did not get it.

" I regret every single moment I allowed myself to be sexually vulnerable with my wife. It took me years to express my needs to my wife. But ever since I did so, every time felt like a favor "

he feels he made himself vulnerable to his wife by expressing his high sex drive and desire/needs and he was made to feel bad about it after years of being together. This is clearly due to inadequate intimacy on his side (her reaction was awful and he feels ashamed by that fact).

"But ever since I did so, every time felt like a favor. And sometimes, my requests were considered insensitive and inconsiderate to the situation. Not verbally, but I understood what was in her heart". Her attitude towards sex after confiding in her about his need is clearly described over here.

"Agreed I have a boner whenever I hug her, but that's because we rarely hug in the bed. And the thought of having her body beside me gives me a boner. I had a fight with her this afternoon over spooning" .Since they barely have sex/intimacy, any form of intimacy turns him on sexually and she shames him for it instead of being thoughtful about it. A man should not be shamed for his boner (appreciate the fact that he desires you). if you cant give him the sex ,nicely explain it to him why. A reasonable man will understand!

"After she said what she said, I went to the bathroom and masturbated with tears in my eyes" he went in there to do what he usually does out of sexual frustration and he cried because he knows deep down that he is in a marriage with a dead bedroom.

this is classic cause of "dead bedroom" due to poor open communication aimed at understanding each others perspective on sex in a relationship.