It's way more complicated than that.
In general i think there's two ways to develop a game. One is to introduce a number of characters and develop the story based on them, which greatly speeds up the progress of the game.
The other is to start with few characters and add more as the updates go by, which makes everything a bit more complicated because you have to pay attention to worldbuilding and adding new characters or developing relationships with the characters you already have.
Also another important thing is to be careful not to rush with the sex content, if it's consensual after that it will feel like there is not much more to do with that character, and that will come into play how could the developer create ''spicy'' situations
Unless the dev have a very deviant creativity, in that case there is a whole universe of content after xD
In the other hand, if it's not consensual, it will be difficult to make the situation integrate into the relationship without making that situation lead too much to where the relationship is going, like what happened with Mabel.
Obviously there are exceptions, such as the Bathroom anal scene with Daisy, but there was used the excuse that Callum was drugged.
I may be wrong, but that's the general impression i get