In my opinion, the realism with the girls is the best part of the game.
In many games, the protagonist can fuck anyone just because he's the protagonist, and the girls simply don't care what the protagonist does.
In this game every choice really affects how the girl look at the protagonist, and the system of the score reminds you how. And if you go up with a girl, you go down with others, you can't be "everyone's idle".
There is no NTR, for the reasons written in other posts (if you follow a girl, it's normal that other girls fuck who they want), there's little voyeurism and only with one girl (and it's normal, in the game you are a group of four, and two of this four are a couple), no harem (only a hint of a possible future threesome), and you can choose if you want romance or lust with your love interest.
For this reason, I have three playthroughs, because it's fun to see every different path, one for every girl.
Obviously, the realism is NOT for the main storyline, but the main storyline is funny because itìs like an Indiana Jones movie, or a Stargate season.