When it comes to sexy times with NPC women they appear to be able to escape from the apartment of our heroic main character if he tries to push them to far out of their sexual comfort zone. This feels a bit off to me since well... our character is an evil human trafficking rapist who employs blackmail and drug addiction in order to routinely makes baby Jesus cry.
Any chance of adding in the ability to... how to put this... strongly encourage the ladies to comply with the more depraved requests of our hero when they otherwise wouldn't? Perhaps instead of running away when our man attempts to put a penis in their throat and then urinate on them, as is custom in what I presume is some sort of Eastern European mating ritual. They might be convinced to stay and engage in these activities due to the previously mentioned nature of our hero. I can certainly imagine this resulting in their new status as an enemy, and they would need to be re-educated on the old farm to become productive members of society again.
TL;DR
Why are there so many limits on my penis?
There is consensual sex in the game and there is non-consensual sex (rape). This is by design. If you want the girls not to run away you have several options. You can get them very drunk before taking them home and also give them an aphrodisiac which will make them horny.
A girl will want to leave for several reasons. If you push her too far too fast or you do things she doesn't enjoy too frequently she will lose interest and leave. Anytime you make the girl orgasm, all previous sins are forgiven (this was added and improved when I did the partial sex system overhaul in version 0.55 Beta). This is where an aphrodisiac helps a lot as it allows the female to orgasm more frequently and more easily.
If you want to rape girls, use the farm. That is what it is there for. If you want to slowly corrupt girls and turn them into sex partners then the normal sex system comes into play. You can then turn fully corrupted sex partners into whores if they qualify.
If you try to rape every girl you meet you'll end up in prison very soon. You'll probably also piss off the wrong girl and you'd end up dead eventually. Even though females are considered 2nd class citizens in Evil 2, they are still human beings and not objects or sex dolls.