That's how most of Atelier's NTR stories go. I think the general audience for NTR games don't want a "good" ending since that kinda kills the NTR mood.Kinda wrong. I tried to give this one a read, to try and understand what can possibly be the appeal of NTR. Yeah, still can't understand. Ended up skipping almost all the dialogue. Only did 1 ending, can't stomach more... and in that ending, the "good" ending, MC and Mia are happy together and chad leaves the country again.
So according to that game (and probably the devs too), if your girl cheats on you, you shouldn't give up on her. No no no, tell her you're there for her, love her, blah blah blah. She'll see the error of her ways. because you see, MC was in the wrong for breaking up with Yumi. He shouldn't have given up on her that easily. Come on man, quit being heartbroken and hating all of humanity and go tell her you love her instead!
There are some rare gems where the MC does grow some balls and stands up for himself but I can count the number of those NTR games on one hand.