As I thought, he feels disgusted by himself for falling in love with a child at the time. My comment on chapter 3 was actually spot on lmao.
Sure 6 years age gap isn't that much when you're old, but he was 18 and she was 12. He was a pedophile for falling in love with such a young girl, and it's normal that he'd hate himself for it.
Marika is still seeing him as her long teenage crush, while he sees her as the forbidden love he had.
@greatninja3 it's not so much about a trauma. Even if they are now adults, going out with her would still be morally questionable. He met her when she was a child and he was an adult, and started to be attracted to her at that time.
Even if they both grew up, going out with her now is weird. It's like, you're not going to date the young girl next door as soon as she turns 18 just because she's legal now. Rather you should question how you came to be sexually attracted to the little girl next door to begin with, and how immoral that sexual attraction is.