First off, there is no ntr. I honestly don't know why that tag is included. There are 2 unavoidable scenes where Mia, the lead female, sucks off another guy, but it's the same guy and the MC is present and consenting both times, albeit begrudgingly the 2nd time, but it helps serve the MC's purposes and leads to a pretty good sex scene with the MC and Mia as well as advancing the sexual relationship with the MC and another female character. Also, the first time is very short and the MC gets most of the action in that scene.
There is also the choice for Mia to tease another male character which can lead to things later on but it's totally optional and future teasing scenes are also optional, or at least you can choose how far you go with it.
Don't let these idiots who are whining about ntr put you off. They're all talking out of their collective asses.