At this point Patreon is your best bet. Technically, there's a lot of content they forbid, but unless you put explicit references to that content on your Patreon page you can generally expect that the Patreon folks will never come looking for it.
It's never going to be a risk-free proposition, but best practices for making a risky game on Patreon are:
1) Avoid putting nudes anywhere on your Patreon page. That's the biggest, easiest red flag. It hurts your advertising side, granted, but nudes on your page are the most straightforward way to get your site reviewed/shut down.
2) Avoid any explicit references to content that Patreon's rules forbit. Generally speaking, calling your game 'adult' doesn't really bug anybody, but avoid referring to 'incest' or 'mother' or 'sister' or any other familial relationship. Devs usually get around this one by referring to characters by their first names instead regardless of their relationship to the main character.
3) Don't post risky content elsewhere accompanied by a link to your Patreon page. If I recall correctly, GiantNut fell afoul of this one. You can advertise, of course, but don't say "check out my incest game on Patreon!" or post stories about explicit incest with a link to your Patreon. That'll ruin your day.
4) Patches/player-chosen relationships. It's not a great solution, and it's not going to work as easily for all games, but if a patch just happens to release near when a build of your game is complete that changes the nature of character relationships and isn't explicitly released by you, that's not your problem and it doesn't tend to bother Patreon.
5) Don't needlessly annoy people online. There's always going to be some crazies out there who say dumb stuff and take things too far, but it only takes one to report your shit to Patreon for you to be in hot water, so be nice.
If you follow those rules, I think you'll find that Patreon is a pretty stable platform for adult game development. It's been fucking killing the taboo adult comic scene, though, since you can't easily patch different relationships into a set of still images (or at least nobody's bothered doing this).