he's always been manipulative. Afterall he gladly hung around Heejae for so long. It's just because he's cute it's brushed aside as cutesy and endearing. it's so weird to me they're all individually awful in some way but it's completely ignored.
Yeah I know, he's done a good job in hiding his bad side but it's showing again lol. I don't know why people hate the two main characters for having a badside when Sunyool is exactly the same and like you said, it's overlooked. Although it does make these characters more human, everyone has there good and bad sides
Because Heejae's "bad side" involved doig a lot of much more terrible manipulative things that are straight up red flags, and not things to work on like Jisuh and Sunyool, maybe ? I wouldn't put their behaviors on the same level.
Then again, in the main story Sunyool was more of a supporting character than Jisuh and Heejae, and got the short end of the stick, so you'd think he learnt a lesson. The other two, not so much. That might play a role as well in Sunyool's bad side being overlooked more easily.
Sunyool, your evil side is showing