Responses

No I think he did tell him, the author just didn’t show the specific scene
I don’t remember the exact chapter but in the flashback where Haejin asks him why he’s been avoiding him they go to the snow and agree to talk…it fades to black so I’m assuming that’s how Haejin knows. Also it’s shown throughout the story that Haejin knows (like when he calls mc out for being guilty or when he notices him looking at the competition book). I’m assuming the author didn’t want to/know how to show the conversation explicitly
just reread this… so he never told him about the plagiarism or the fact that he left him in high school bc of the guilt and feeling like he killed his dad???? they just agreed to bury it? idk kinda lame that had no payoff