I think the first rape traumatized him so much that he used rejecting his friend as an excuse. This excuse even mitigates the rape, because he tells himself that he deserves it, and therefore that he has to pay for what he did when he just doesn't want to accept the fact that he was raped. Abusive relationships reinforce his denial. I may interpret the story too much but I find it believable.
I like this take so much. I hope katsumi can get help or therapy in the future. Your lover shouldnt be your therapist and all.
So the FL raped the ML...
That's what I had said like she just couldn't accept the fact that he didn't love her anymore so she drugged and raped him