Dude literally added it over a year into development... with no warning. What else is that than milking more $ ? There's no need for the demographic it had (and lost a lot of).
Your point makes no sense given the facts. And same will probably happen here.
Also it does ruin the game, it makes the LIs involved cheaters, which MC has to stop from cheating, but they still would cheat.
That's how narrative choices work, characters only ever act in ways they would choose to, so if you add such choices it becomes part of that character.
And people simply choose, to leave the hoes to the streets where they belong.
p.s. although given the game you have in your signature, I guess dev honesty, and keeping their promises don't matter too much to you.
The dev is free to add whatever he wants, whenever he wants, I'll agree that a warning would have been very much appreciated though, this is something he is being paid for after all, honesty is very much important, but I still fail to see how that is "milking", again I think you're just picturing him as some sort of villain that had this whole thing planned out from the start, I'd rather give the benefit of the doubt that he didn't leave people in the dark just because he wanted more money, "Never attribute to malice that which is adequately explained by stupidity."
"There's no need for the demographic it had", I'm not sure if there's data on that, but I guess we're just going on the fact most people don't like NTR, which is true, but should every decision the dev makes be completely focused on the current demographic he has? as I said I think he has the right to add what he wants to the game when he wants to, even if it's to branch out to a minority, once again a bit of transparency about it would have been good, but he nonetheless has the freedom to add what he wants.
I can see where you're coming from in your view that it "makes the LIs involved cheaters", I guess that is a deeper problem with how it was written and implemented into the story and how you view the characters, I understand why you would feel that way, but that isn't really the point that I take issue with here, your feelings about the NTR itself isn't what I'm questioning, I want to make it clear that I don't think you disliking what happened was in anyway wrong, nor is your distrust unfounded, I just think that immediately acting like the dev is definitely looking to milk people that like vanilla before backstabbing them is a less than honest way to look and describe the situation.
I won't press it much further because I know mods don't like people arguing over this stuff, and besides it's not my job to defend the dev.