Developer should cater to the Harem and NTR crowds instead of alienating both.
For example, when you're inside Fina's house, you see a picture on the wall of her getting cummed on by multiple men. In that moment, the player should be given a choice:
a) "Fina looks great getting fucked by all those guys, I'd love to watch her get fucked live while jerking off."
--> ADD QUEST: Become Fina's boyfriend and cuck, and watch her get fucked by tons of guys.
b) "Fina looks great getting fucked by all those guys, I wish it could be me getting fucked instead of her."
--> ADD QUEST: Discover how Fina seduces so many men to gangbang her.
c) "Fina looks great getting fucked by all those guys, I wish I could be with her, helping her getting fucked."
---> ADD QUEST: Join Fina's Gangbang as a bitch, like her.
d) "This is some bullshit, Fina should belong to ME and me alone."
--> ADD QUEST: Conquer Fina and make her yours alone (Harem).
e) "Fina looks great getting fucked by all those guys, I should get on good terms with her, to join in and fuck Fina along with those guys."
--> ADD QUEST: Talk to Fina about joining her gangbangs, to fuck her like a bitch, along with the rest of the guys.
f) Other...
This won't require extra art either. Based on the existing art, these specific fetishes can be catered to, all with clever use of boolean flags and dialogue choices.
Dialogue choices make content more engaging for the player.
Making decisions for the players fetishes is the easiest way to hurt your revenue IMO.
Now, if you have to make extra art, then yea, you can't just add content like this, but his current art assets could easily cater to a wide variety of kinks. Kinks he's obviously already into.
I would never leave this kind of feedback unless the game already has massive potential to be TRIPLE A. So when I leave this feedback, it's a huge compliment to the game. Other games are so fucking bad, they don't even deserve criticism, because they are beyond hope, lol.