Not true colors but more like he have been through so much pain and betrayal and never really felt love and his only comfort was his love for suha wich was taking buy that red hair fucker but then he could reach suha and tried to proof his Love toward him and tighten their relationship but then shit again happened and he unintentionally hurt suha so he's scared of loosing him again buy grasping on him you can see that he looks tired and his eyes looks lifeless he needs insurance about their relationship
sure he doesn't want to hurt Suha, but his obsession does not make for a healthy relationship. even from the beginning, you could see how riled up he got about the idea of Suha being with other people, how he reacted whenever Suha was sexual with other people (when they were just hooking up in the beginning, and later, when Suha had merely masturbated), how he pretty much made most of the decisions as far as Suha moving in with him, his micro-aggressions towards Suha's coworker and friend, how he is now keeping Suha from his place of employment, and most recently, the raws (wow).
I think it has been a slow build up of Jiwoon getting what he wanted.
It's called 'My Suha' for a reason.
hes not toxic, hes more controlling. I mean yes, he does care for Suha, and yes he likes him but I think he did it because he likes him and not because hes trying to be toxic. So I dont know where some ppl got the word toxic from but yes he is def bein controlling but only out of love.