Me: total top, partner: versatile

I’m new to the sub but I have a question that I would like to get some input on. I am in my third long-term relationship. I have always been a top and that’s all I’ve ever professed to be to my partner. He is versatile and holds the opinion that I am being selfish for not wanting to bottom for him. I actually did it once and it didn’t do anything for me, but he holds it over my head. He’s actually admitted to withholding sex because I won’t bottom.I don’t think I’m being selfish because I never professed to be vers, and I did actually bottom for him. Even if I’m being “selfish” I don’t think it’s right for him to withhold sex because I won’t do what he wants.We have had many arguments about this and it’s not getting any better.Thoughts?