I don't know what to think about our MC a his feelings towards the "mother figure" of Rachel,
because in some cases he talks about how she neglected him in the past, she doesn't care if he was bleeding after the school fight, etc. etc. He expressed himself that "he'll not forgive her that easily" yet we never see that. MC's behavior towards her is rather friendly I would say.
I simply don't belive him that after so many years of Rachel's abuse, MC would jump on the first opportunity to grab her titts. Maybe he has some mental issues, that would explain a lot.