Ok, so now that I have it clear, here is where MrDots games stand. All of them, going forward.
Per Jeff Steel (developer for MrDots games) every single game going forward, including this one, if the MC sleeps with multiple characters, then so will the primary LI. It's not NTR though, it's just so it's more fair. In a porn game. Because that's what people want in porn games. They want to form meaningful relationships with a single female love interest while tons of hot girls throw themselves at the MC so he can reject them. You know, as much like real life as possible. Because, that's why people play porn games, to have an experience as close to real-life as possible.