"I think that programmers are far away from being able to create a simulation of a realistic sexual encounter"?
No. I think programmers of all kinds could make such a simulation.
It is just that they don't want to.
Why? Well, for one, there are such simulators. Just google "3D Sex Game" or something to the like. Other than those games, however, games have no reason to feature explicit sex scenes.
I, for one, do NOT want sex in any way shape or form, in my games. I think it is simply explicit(for the sake of being explicit) and completely unneeded.
I don't play DA:O to romance characters either, so maybe that influences my opinion.
I say people actively looking for sex and romance in games should probably hit up "Dating Sim", "Sex Sim" or the aforementioned "3D Sex Game" on google - It will satisfy all your needs, I'm sure.
EDIT:
To make it clear: Romances can be fun and good (although the vast majority aren't), but I feel (the depiction of) sex in a game is contrived and meaningless.