I don't remember him being this insecure, what the fuck happened?

He's always been like this since forever, it just that it more "subtle" before. He literally always glued to Yihyeok since their childhood and keeping away others so it's always him and Yihyeok (but bro can't really beat the extrovert Sanho for some reasons). He become more "open" like this i think that's bcuz both of them have feud in main story to the point that Yihyeok didn't want to see him anymore (ended in a month)