This last chapter was really strange indeed. I think the author's idea is that Myunghan's mom never knew about his son psychological problems since they weren't even talking to each other. She didn't tell him about Sihoo's condition because she didn't think it was relevant anymore after he befriended Seungchan, and then as time passed the topic was simply forgotten. Again because she never knew it was weighting heavily on her son. About Sihoo's reaction, again, it's really odd. Maybe it's the author's way to tell us that Sihoo has moved on and this reunion didn't really mean anything for him, or my theory is that there's still much more that we don't know and maybe there's some convulated reason behind Sihoo's action.
I really don't know tbh, I hate plot holes but I'm trying to at least give the author the benefit of doubt by largely interpreting what they want to tell us but it's getting hard and honestly, I just believe they should've done a better job with some of the exposition.
I would like to add to iSexy's remarks about Myunghan's mother: I can't accuse her of bad parenting nor hate her because she DID try to reconcile with Sihoo's mother for her son's sake (after all, it didn't seem like the entire families were friends with each other, acquaintances at best) and it just seems that she not only felt so much guilt over her failure but that she also wanted to spare her son the pain of knowing he wouldn't be able to see his best friend even though he was alive because Sihoon's b**** mother blamed them both for the accident. For an impressionable little boy that could have lead to him destroying himself with self blame and guilt. I think his mother wanted to spare him that. And when she saw how happy he was with Seungchan she thought he was finally forgetting Sihoo, or, at least she was hoping he was.
that last chapter was pretty underwhelming in the sense that we find out that his imaginary doppelgänger for his childhood friend is very much alive, but that Myunghan's parents had known that there was something very wrong with their child, who had internalized his trauma and guilt could have been spared of this entirely had they simply told him the truth 10 yrs ago. Sihoo's mother is clearly a bitch for blaming a child for what was clearly an accident, even more so an accident caused partially by her negligence and her own son's recklessness. Separating the children, for your own peace of mind in justifying your anger and blame on Myunghan is deplorable, but seems to be a running theme in Korean manhwa/entertainment of scapegoating parents. (Sidenote watch a Korean Drama should you get the chance and almost every plot has parents who will at some point ruin someone's else life and place blame on either their child's love interest or friend, literally every time). I mean what's the point of keeping the status of Sihoon's health a secret when especially it resulted to the point of Myunghan becoming a social pariah with acute anxiety? You're truly a bad parent if it takes you ten years to excuse your personal problems as reasons enough to prolong combating your son's deteriorating mental health. Secondly the friend's reaction to being reunited to his childhood friend was so blase I have no words to describe how insulted and annoyed I'd all at once. Understandably he provided the closure that Myunghan needed desperately but i'd reckon he stayed for no more than 10 minutes when they have 10 years of lost time to catch up on. You might have your own life, but sparing 10 minutes even for your old childhood best friend is that much to ask? Seriously? More so because you know he called you out of the blue, shouldn't his unexpected contact seem worthy of fully investigating for its cause? Or better yet fainting at least some curiosity? I feel so let down by their reunion if i'm being honest, and just angered by how many people failed Myunghan up until this point in helping to rid him of his "ghosts".