wow imagine shunning your friend cuz he told the truth about your feelings to another frie...

i think i can kinda understand though. i’ll think something bad about someone, but it doesn’t mean i hate them. but if someone spoke on my behalf about something i wanted to keep private, i wouldn’t be happy. also, the person who i thought badly about would have thought i was badmouthing them when in reality i never said anything or told anyone

i sorta agree. People aren't perfect, and sometimes I have times where I complain about my friends to other friends, and vice versa, and there's a general agreement to not tell anyone about it. Sometimes people just need to get it off their chest, doesn't mean they're deceiving or inwardly hate their friend or smth. If someone did tell them ur private thoughts and caused you and your friend to fight then yea it would be a little sucky but also not entirely their fault either.
But either way those friends still suck lol.

I don't even badmouth my friends, in fact, I do talk good of them, or talk to my other friends about things I worry about my other friends or things I admire of them, but even if what I say is not mean, I would feel a sense of betrayal if the friend I talk with starts babbling their mouth about our conversations, I would feel embarrassed, and a sense of betrayal.

"told the truth about your feelings" that's the thing with feelings, as a friend you don't have the right to expose them, if it's something that was entrusted to you, you should keep it.

I think what is bad is that he made everyone in the class not talk to MC which is wrong.What the MC did wasn't nice but still not a good enough reason to shun someone completely .Also who the hell keeps talking about the same middle school incident till uni to make the MC lose his friends.You do a lot of stupid stuff in mid school but people change when they become an adult a lot of times so don't hold them accountable for this stuff for eternity.