@boag The rape is not the primary cause, the rape is what puts him in a vulnerable state and in need of help, but his current problem comes from somewhere else, his current problem is a product of how he managed to dealt with being raped, and is Sensei's fault.
He feels like feeling attracted to women is a bad thing, to the point that he only got an erection the moment he started handing out money thinking that he needed to give it as a form of compensation, as if what he was doing was wrong, because on his mind he still thinks that sex is not enjoyable for women, so to deal with the guilt he handles out money.
But the whole point of this sex encounter was to show him that women can also enjoy and like sex, and he ruined it, he completely ignored it (and by extension he also ignored the girl he had sex with), matter of fact i think that he has become worse now, he is embracing the twisted idea that it is ok to have sex as long as he somehow "fixes the disservice" by using other means, and on top of that he thinks that women transform into things the moment they start having sex, so for him sex is something horrible that can rob women of their humanity and value, so he has to repay them somehow.
And that idea was sold to him by sensei, before talking to her he was afraid of women and saw himself as a victim, but sensei managed to twist the narrative and make him out to be the bad guy, and now he feels bad about it, he started thinking that it was also his fault that he was raped and that as a man he had plenty of opportunities to just avoid having sex with the married woman, is thanks to her that he has this obsession with defending women from evil men, which are all men because all men have the power of penis, a power that women as weak being can't oppose, while also feeling guilty about the idea of becoming another one of those evil men so now he hates himself and his own lust.
Except... he now came onto a convenient solution, unlike those other evil men, he is giving back something to those poor women, even if little, he can pay them for their trouble, as if they were porno magazines, so hilariously enough he is becoming a truly scummy man.
I think that Sensei is trying to hook up with him because she has figured out that he has embraced her own twisted ideals (which he has), so now she has a kid that she has indoctrinated and that is easy to control and experiment with, she has access to a man that feels so bad about being a man that will never try to oppose her, and thus she can now try that love life she never had the chance of having.