It's about more than being bisexual. Damon is perfectly happy being a man. He's never even been curious about what it feels like to be a woman. He wants to be himself, in his own body.
But because he's currently female, doesn't mean I don't still love him. It's just...sex isn't a thing right now. We're both very straight, and he's not comfortable. At all, and probably won't be until he's him again. Even if I did like women, I would never push him or come onto him.