Nasa so chad, HE DEFILED ALL MIGHT TRUCK-KUN AND LIVED, JUST TO ASK HIS CRUSH TO MARRY HIM... and she, so impressed his to shoulder bone-crushing pain and blood loss, said yes. The man was willing to risk his life for love and despite tremendous hardship, he siezed the opportunity.

Now, correct me if I'm wrong, but Kazuya did, in fact, confess to Mami, and she said yes... then broke his heart a month later because she's too much of a bitch to stand up to her parents. Then, not keen to set him free and leave him be, she has to destroy his self-worth to ruin him for any other girl. Thus, he resorted to simping just so he could FEEL something again. Now, he has girls interested in him and he doesn't know how to deal with it but to keep simping.