Where are the flaws? That the guy was attractive and managed to seduce others? He may have gone with other people's wives but that is on the wife to say no, not on him.
I do not believe “that is on the wife to say no, not on him”. If these allegations are true, he was a teacher engaging in predatory behavior. That is simply unethical due to the power imbalance. And the fact that he was asking people to cheat is unethical.
This is how the crime of "Solicitation of Murder" came to be.