So after lots of painful considerations I finally figured out what I wanna do to make sex system more dynamic.
Firstly, lets get out of the way the obsolete thing: separation of action points and energy points: there's no real reason so have both, so action points will be displaying energy points instead, and all actions will be using those.
Now, to make sex progression system less arbitrary, most actions will be locked away. You'll only start with 1-2 basic actions (depending on the slave) and other actions will have to be unlocked by lewdness points (or whatever name will be used). Plan is pretty simple: you interact with the slave, and you get their affection (depending on how happy they are from interaction). More affection and contacts - more things they will allow. I'm still figuring out how actions will overlap, but there's lots of possible options: item usage, clothes, what slaves would ask if they liked it, energy costs and reductions. All in all it should feel like you actually getting somewhere and making choices. Also sex related jobs will benefit from it.
This will require quite huge restructure of current sex scene screen and mechanics (which are also poorly coded), so might take a good over a week or two. Besides that I got couple of thoughts about Emily's quest continuation and I'm planning to finish it in the meantime.