ETA2: Just saw your developer's note:
First up, dont sweat it. No one expects Chekhov. You have your main framework? You know where the storyline is going?
Second: You have the motivations of the various characters outlined? You know what they all want? Do they have flaws that can be preyed upon. I mean mr OP (should be clear, i mean main protagonist not op of this thread), was pretty easy to seduce and boss around for someone who thought he was in the drivers seat of his relationship.
Third: Where are you putting your player choices, and how do they have consequence (i'll have to explain this), but if you want to skip the description, just play "Being a Dik" and see someone in complete mastery of this.
Lets take the Danni scene i earlier objected to (where you punch her at the pool).
Right now scene goes from bedroom, teasing and mischief into a blowjob. At no point does the player get to intervene. He is going to completely accept the blowjob; he is going to betray his fiance whom he is ALLEGEDLY in love with... (thats all it took! some mild teasing!??!)
Imagine instead if danni did almost the same things, but you had a few key points in the build up where you could back out through a player choice.
Now me as a pervert wants to see the renders. But me as a gamer wants to act in adherence to how id try and behave with the person im in love with.
But you have this narrative beat you need to hit. The MP needs to be locked up for something... Well now we have to be creative. I mean, if the player told danni to back off and she still kept coming, then perhaps by accident he tries to wriggle out and she falls (then makes up an abuse story). Perhaps he does sock her in the face. Perhaps, worst of all, she watches the op go and we have a scene where she fabricates the story to one of her friends (you've already shown many times that she is super manipulative with cut aways). Well now, poor MP (and player) is an innocent sweetheart (just trying to keep his shit together in this world of lunacy), yet is condemned as an absolute monster and has no idea what he's done and why its happening (or how to defend himself).
And this really impacts into the choice you'll end up making on which route to go in... do you as a player want justice, revenge on this entire family? (bite route). Or do you just think 'it's a complete misunderstanding! Im sure it will all be ironed out eventually!' (sub route). Or is your entire goal to prove to your fiance that you're innocent, that you'd never betray her, and you're being set up by the very people currently showering her with praise? How to do that? You could destroy them from the outside (take the bite), or from the inside (let them play their games). Ooof! so many story threads spilling from the sky!
Now lets go back to that choice... what if you took the blowjob. What if danni dropped her pants to reveal her dick and expected reciprocation and he told her 'fuck no'? What if perhaps she then threatened to blackmail MP by telling his fiance how he came onto her, how he kept trying to fuck her. How she didnt want to betray her sister and her family? Well, now, for pure anger related reasons and not just 'oh no! am i ghey?!??!' reasons he feels he has cause to throw that punch. He still thinks he's in control of the situation... nothing immediately changes, until it does. But... he did kind of betray his fiance... he did kind of throw that punch in anger. He did sort of end up there by his (the players) choices. But now that decision again carries a different weight in chapter 4 (is it?).
Is he going to trust these assholes for justice and equity? Rape? I only punched her. She was blackmailing me. And this psycho with her torture implements... and wheres my fiance? I saw she was changing. Becoming one of them... (your story beats). FUCK THESE ASSHOLES!!! Or does he think if he plays along, perhaps he can expose danni and the whole lying shit show (sub route - even though hes a lying, manipulative, mendacious asshole on an objectively moral level).
Whatever path. Whatever story, with just a couple of extra scenes and some well placed player choices (whether i call danni a he or a she seems to just be a choice for the sake of it, for example), you put the agency in the player's hands (superficially). You can still push the same narrative, but now its got some agency and teeth to it.
I hope that helps. Choose the points where decisions have consequences. Make those consequences prey on the player's... ahem... urges. Give them what they deserve.