People can have attractions for certain genders, orientations, etc, subconsciously, before they realize they are LGBTQ.
When I was with my ex husband, I responded to him only when I mentally detached myself and thought of him as a male stripper I'd ordered from an online catalogue (Luckily, he looked the part, and to my shock, loved the idea and played along).
I could only kiss him when I pictured myself as a guy.
Mystery solved now..after I left him and moved to Thailand in 2010 I found out I'm partially transmale, and he recently contacted me to say he's decided to live as a women, although he considers himself "other."
People tend to imagine what they must, to accept their partners physically, and can offend partners with their fantasies.