Why is it that when someone does a sexual favor for me, suddenly it’s not sexy to me anymore

Like, I have all these fantasies. And desires. I have so many things that turn me on when I see them or think about them. But anytime someone says “what do you want” and offers to do something for me sexually, and I try to have them do one of my desires, it’s like it’s suddenly not hot at all. I feel this immense pressure to find it super hot because they went to all these trouble of doing it for me, but I just feel nothing. It makes me feel so lame because people are always saying “what can I do for you, I want to please you, I’m at your service” but then I just feel so uncomfortable even asking and then even if I tell my strongest fantasies, I will just feel nothing when they do them. Anything at all that is framed as “I’m doing this for you” will immediately lose all of its sex appeal for some reason. It makes me feel so sad because I want to experience these fantasies and experience being serviced but I just can’t figure out how to.

I enjoy doing things for others, and that gets me off, but I have my own desires too. I feel so bad every time it doesn’t work. I’ve never even reached orgasm from a partner because the moment the focus is all on me I just can’t. I’ve always had to touch myself while they get off. And it’s not just one partner or one desire, it’s been all of them, every time.