I know, for me, I'm sort of on the bi spectrum. Before Moonlight, I'd been attracted to women, had sex with a woman a couple times, but she was the first I'd ever wanted a relationship with. And, while sex with her is hot and beautiful and fantastic, I have a much harder time getting "in the mood" for her than with Fly or Punk. So, to put it in slightly comic terms, I'm bi, but not that
This has definitely been challenging for Moonlight, especially since I was raring to go all the time when we first met. Luckily, she's been patient and understanding. I find that it's a bit like going to the gym; I don't really want to go, but I know if I just do than it will feel good and make me happy. So, sometimes I go with it and "the mood" comes upon me as things heat up.
Sometimes, having some cuddle time without the expectation of sex helps. If I know she's not expecting the full meal deal, I can relax and enjoy her touch and closeness. This often leads into having sex, because any stress about disappointing her has been taken off the table.
Anyway, hope you can figure things out!