IMHO only. I think many people use fantasy to create an orgasm. I'm not sure what else to think about actually when I'm trying to have one. I fantasize a great deal during this time & I see absolutely no harm in it. Honestly I've been doing it since I was a teenager. But that doesn't mean I I'm cheating or disrespecting my partner. I think this is where societies judgments can crawl into our bed.
What is so wrong about having a fantasy if it helps you orgasm? Can you change this fantasy? Yeah I think you can; add & subtract from it if you want. You came up with this fantasy of this other man in the first place so that means, to me, that you can also change it too. I'm not sure where this rule book is that says I'm in bed with this person & can ONLY think of this person & if I think of something else I'm a bad person. Bull.
Practice trying to change it. Try it.

With your orgasms it sounds like you've practiced edging, ?? which helps build up an orgasm. But with women there are different types of orgasms too. If you're having all your orgasms from clitoral stimulation then try to focus on other areas....of interest. This is where "R" comes in very handy...& toys.
Wish you the best!