Review Detail of qianlin in Kill the Sun

I've read to around chapter 330. I haven't been this disappointed by the way a story developed in a long time. World building is fantastic. Characters are written alright, the author tries to give them depth. MC is an idealistic guy, though too much time is spent writing out his spiral of depressive thoughts...anyway. Friendships were being built, plot was thickening nicely, and then in the span of about 10 chapters, the author just took it all apart. MC goes down a rabbit hole full of wildly out of character decisions- more akin to a Marxist madman than the naive teenager he has been the whole time. One of the likeable/important side characters started getting some nice development, then gets killed off in a forced plot twist, taking with him the reader's hopes for the rest of the story. MC continues on with no critical self reflection, no coping mechanisms that make realistic sense, ethically bankrupt actions that severely misalign with his past traumas and determinations...as far as I can tell, he loses the sympathy of most of the audience and readers start dropping like flies. Author, just what were you trying to do??