itch io went down for near a whole day right when I was about to send this reply O_O Anyways...
One thing I would do is minimize the amount of the body that stays still between frames. It's very noticeable, especially at full-screen.
Secondly, if it were me doing the anims, I'd probably have a foreplay/stripping animation -> sex animation -> orgasm animation, and maybe he'd come first with some partners, maybe she'd come first with others.
That's just how I'm planning things out for my own games, though. Feel free to use that to improve your sex scenes if you like.
I noticed another bug, in the stages between bosses 5 and 6, a lot of enemies and projectiles would hide behind the UI, and sometimes the screen would flash red with no warning. It might be that projectiles and attacks hide in the background image really easily, making them hard to notice, but it might actually be the player randomly taking damage