
what i didn't like is the MC getting off on mio knowing he is having sex with someone else he should be jalouse and more angry but he was horny

Well...guys physiology is weird. They can even get boners when the wind blows.
And he might have already had one while he was sitting on the toilet thinking about Mio and questioning things.
He might have just been swept away by it because he wasn't really thinking about how Mio was getting done (by someone else) but that Mio getting pleasured like that turned him on.
Besides...some people do get on seeing or hearing others fuck their lovers. People have different kinks. We can't judge them for that.
it is all about RAPE , S&M and CHEATING there's no Romance here. I didn't like any of these stories ヽ(`Д´)ノ