
Looking to all the flashbacks, i think Yeonwoon left because the older brother beat him up really bad, and i'm guessing the mother gave money to his father to make sure Yeonwoon didn't speak, and maybe he doesn't want Seo-in to know because he doesn't want him to think that was his fault, i'm really exited for this season

So, i read the novel, and for those that are worried that this will be some toxic behavior from the characters, well not that much, their relationship is very cute, at the beggining uke tries to keep the relationship casual and hurts the seme sometimes, but seme is very straightfoward with his feelings and makes uke fall for him very quickly, when they are oficially together their relationship is very healty and wholesome, sorry for my english, this is not my first language
I really hope that the side effects of this drug are reversible, idk how ML will come back from this, i hate him already