I just tried to think of a turn off that is not is not directly sexual or related to sexual kinks but I have come up with nothing.
So I have thought about it and come up with something I actually really, really dislike.
Player Choice.
This is a buzzword, Ubisoft and EA executives will throw around when developing their shitty radiant quest open world games. It barely belongs in gaming and especially not in erotic games.
The people who play your game want to experience all the content. They all have some sexual scene they prefer, and making it available to them is in everybody's best interest.
I need examples to describe this issue better, so I am going to rank some games with player choice, and rate how poorly it is implemented:
Four Elements Trainer: This is probably the best implementation of player choice available in a pornographic game. You can get a different story, with different scenes and a different relationship to your sexual partner depending on an initial choice of "love" or "slave" route.
While this still binds you, and essentially forces you to replay the game, it is done well. ALL of the sexual content is different. blowjob scene for Azula depending on whether you are in love or if she is your slave are vastly different, come up at different times, and uses completely new CG. The story is also different, not just at specific points like the games below, but almost every word of text is different.
Here is an important part: The creator only works on one route at the time.
Considering the business practices of developers on patreon, I think it is very fair to judge games on how they are progressing, and not just the finished product. Four Elements trainer only works on one route at the time, meaning everyone who is playing it is going through it together. It also means whenever there is an update, it will be relevant to you, because the content you are looking for is not some niche stuff hidden behind a choice you didn't make correctly several updates ago.
Dreams of Desire: In this game you get the choice of having your sister love you / be your slave and the choice of whether you want to help your friend get laid too / keep all the women for yourself.
Turns out these are actually minor choices. Alice and Marcus' mother are not even half the game's content it is probably closer to 25 %. And guess what, most of the Alice scenes (the bulk) are the still the exact same, wether she is in love with you or not.
This game is so vast though, you will need to have several saves to and replay the game at least 3 times to get all the content. The game is a visual novel, so replaying it is mostly holding down shift until you reach the relevant choices
Dating my Daughter:
Similar to dreams of desire, the choices here are meant to gate content, content that may be unwanted. Sadly some of these choices are far reaching enough that they can be called routes. You have to cut off content with some girls to get with others, while realistic (realism in an incest game?), it forces replay-ability.
The replaying is holding down shift until relevant choices occur, but it is to a MUCH worse degree than dreams of desire. This game features so much hand holding, kissing, accidentally touching, replaying this game is a lot more grindy and less rewarding.
A new Dawn: The absolute worst example I can think of. This game has 3 routes, separated in the beginning, all with an EXTRAORDINARILY huge grind, and yet share most of the sexual content. No one in their right mind will go through each route of this game. To describe the grind, basically you have to spent a stamina bar each day before you can continue to the next, doing so requires alot of clicking and button mashing, while moving around in a RPGmaker town, going to bed, realizing you forgot to pay taxes and eat, leave your house to do so, now walk back and save the game, and reload until you get the dream that will progress your story. Unlike four elements trainer, each route is being worked on at the same time, meaning the game will progress extremely slow, and some updates wont be relevant to your save.
To summarize a little: If you want player choice in your game, make sure that the consumer actually want to play your game several times. In you include some kind of grind (new dawn) or stall with unending irrelevant scenes (dating my daughter) playing through your game more than once is a chore.
I understand that the idea is for the experiences between routes are to be different in the finished product, not necessarily expecting people to go through them all. But that is just not the case anymore. You are not selling a finished game, you are selling monthly updates on patreon.