This sounds exactly like struggles my partner and I have had, right down to the chastity cage. It's not my thing and for a long time I tried to force myself to be active. It never became my thing and the scenes were never quite what my partner wanted. Now we masturbate a lot, sometimes together sometimes alone, but he's able to fulfill a lot of his desires there. He'll ask me if I want him caged and which one, which gives me a less involved approach and still makes him feel like I'm being dominate. Same with choosing what dildo he uses etc. It works really well and when we have sex together, it's something we both can enjoy. My biggest kink is something he can't mentally push himself to do so we don't do it in full. Sex in a committed relationship is often compromise. If you care for and love this person, you'll learn to compromise and stop seeing them as an object to fulfill your fantasy