This is adapted from the talk I gave at NYU Poly about my free spanking game Hurt Me Plenty. It kind of "spoils" it a little, if you care about that sort of thing, so I recommend you play it before reading this post... Or watch Pewdiepie play it, I guess.
You can imagine Hurt Me Plenty with its realistic representational graphics as a critique of the sex in contemporary Western video games with similar graphics, such as in Bioware RPG games (Mass Effects, Dragon Ages) which regularly feature "romance" storylines that climax in a cutscene of two virtual dolls glaring at each other for a few seconds, with cold unfeeling eyes devoid of human warmth, before tastefully fading to black. (My game hides your partner's face as much as possible.)
These kinds of representations are dangerous more for their structural properties: players understand these romances as puzzles to be solved where sex is the reward -- and the idea that sex is a puzzle reward feeds directly into a pick-up artist (PUA) culture built on manipulation and perceived entitlement to bodies. This is essentially the "kindness coins" critique, that the logic of training players to expect sex, based on a series of so-called strategic actions, is super gross and perpetuates damaging ways of thinking about relationships.
Instead, sex must be more than a node, it should be simulated as a complex system in itself. Sex must not be some sort of reward or foregone conclusion. What if we represented sex in games as an on-going process? What if we actually did sex?
Several games have explored this already: