Is this a first-person POV scene for her? Or third-person, more distant?
I often have a hard time with plots that jump humans and aliens into bed together quickly, even when the aliens are very humanoid. (I am not saying that's what you're doing!)
Even if the required, um, equipment was compatible, I'd think it likely that aliens would smell quite different up close. Would feel different -- difference muscles, different bone structure, different skin texture. Now, maybe I'm just a very tactile kind of guy, but that would be an enormous speed-bump for me personally. It's one thing to idly daydream about that cat-furred "lady" who works down the hall, but when she's actually laying up against me? Umm, this is kind of weird, and she smells like burnt toast, and she's biting a bit hard is that going to get worse, and what the hell are those on her back?
Not that others might not feel differently; different strokes and all. But I doubt I'm alone, and when a story just breezily glosses over that speed-bump, I'm always like, whoa. Really?
So, I'd want to know about this character who is attracted to an alien. What's going on in her head? Is she both attracted and repelled? Feeling shame that she's attracted? Confused? Was the physical attraction preceded by emotional bonds? What is she thinking, as she takes the plunge into a physical relationship?
Frankly, what is she feeling in the moment? Equipment's a little different; is it better / disappointing / uncomfortable? I don't think you must get terribly explicit here, but glossing over it or reducing it to clinical summary does seem like a missed opportunity?