Hux never really has had interest sexually in humans, instead finding comfortable intimacy in droids who in the end he had ultimate control over as they’re just machines. Kylo then enters his life and with wild speculation from the crew of (among other things) maybe him just being a droid under that mask, Hux finds him fantasizing about the man. Kylo’s a virgin and is intrigued by Hux’s sexual history, even if it’s not his thing. Everything’s strange, but somehow it works for both of them.