Will there be permanent defeats? if enemy encounters increase from losing battles it can go either having to run through mutants or over and over or a limit to how many losses until a hard loss is given.
I imagine impregnation would be it, or corruption to the point Haydee won't resist, lewd thoughts increase, desire for sex increases.
It seems the route this game's going is action first, sex is secondary (games like this would have sex only happen during defeats or triggered by certain events), that's fine if its your goal.
If no sex skills are going to be implemented, maybe a "hard" mode? Armor is more rare and so is ammo, maybe instant - loss moments, corruption is more easily filled, maybe an enemy will keep the Haydee for longer after losing a battle unless she escapes if she doesn't want a 2nd creampie or more, leaving a mess.