safe NSFW
That's a good one.
But joking aside, try Steam. The more mainstream, the more vanilla. The less mainstream, the more nieches you will see that you will not be comfortable with.
This goes for regular games as well. But usually we go, meh and move on, and not belittle people playing or developing it. For example idle games. Players of those get their fair share of ridiculment. Adult games are just an excuse to see some lewd pixels and have it be more interesting than watching a movie. And the folks here are also here for the "bad" games. Amateur developers and the rare gem they find. And concepts and game play experiments you just do not see in mainstream.
Actual rape content is not allowed on Itch. But this is in the eye of the beholder. A murder simulator would also not be allowed, and still this is the plot of most rpg. Context matters. It is the gloryfying aspect that gets games banned. You can show rape in movies, why not in games. In fact it is a major plot point of many movies. Banning the thing itself without considering context is pointless. It is a bad thing. So is murder. Using it to show something bad happens is simple story telling. A female prot game featuring this often has this as the negative consequence to avoid and overcome.
I wonder why you did not complain about incest. That nieche actually is "popular" on Itch. And I can explain why. While not illegal - hey it is pixels and made up! - , major platforms do not allow it. So it is seen more on platforms that do not ban it. Also, anything "step" is very popular on actual adult sites.