That's too bad that he has no desire. I have more or less the opposite problem. I had heart surgery at 56, 72 now. They loaded me up with BP pills effectively killing little njoy. I still want to but he can't and my wife is fine with that. Once in a while she lets me rub her off but she refuses to let me stick a finger inside her.
Even though little njoy can't salute, he can still come. It's kind of like having a large clitoris I guess. He gets all the good feelings and he still spits, I just can't get a grip on him ---- have to use two fingers. :-( I keep him well exercised by making him spit several times a week.
Maybe he IS masturbating but if you were as enthuiastic as you say I don't see why he doesn't share that with you. I would love to have my wife do it for me but she has no interest in that at all. I think she's happy that I don't bother her any more, she never wanted to touch ME anyway.
Have you tried to do other methods? If my wife was into it I would love to do her with a dildo or whatever she likes. If I was operating the dildo or whatever, I would enjoy that almost as much as using my built in toy. For me, pleasing her was my greatest joy of sex.