Alright, I'll try to be more constructive.
It seems to me that the author didn't have a clear idea of the story from the beginning and is improvising a bit. My advice is to write all the narrative archs before developing the AVN.
There are also several problems with how the adult scenes are built.
There are too many characters that interfere with the stories of potential LIs. You don't see a character for half an hour then suddenly you meet them again and the relationship move ahead so quickly that you tell yourself "wow, that's a quick progression!".
Also, I like the casual sex but it lacks pathos and eroticism.
Man I know it's casual but this is just shallow.
My advice to improve a litte: try to focus on the most important characters, describe their feelings, write some dialogues with the MC where we can get an insight of what are they feeling.
In my opinion, the story isn't a progression of things the MC must do but a narration of how the relationships are built and progress then you build the story around this.
I hope this gives the developer some things to think about because I like this project and I don't want to see it descend into mediocrity. It's a 4 star rating on here which is already below the good quality treshold, let's hope it doesn't go below 4 stars.