Responses
I believe its bcuz siwoo is different compared to the other people he met.. so he craves the attention and kindness that he never received since he was young towards siwoo.. thus, the possessiveness and anxiety of losing him to someone else.. he is not used to this feeling.. i find his character interesting because of this.. Will looking forward for more chapters.
I can see judging from his Expressions and eyes, he is not used to expressing his feelings to other people or know how to say it out loud. The type of guy who tends to follow what other 'rich kids' do aka the trend.. he doesn't technically know whats actually morally right and wrong because how he is treated by his relative (assuming his grandma and parents). With the constant of comparison with our OG ML. He definitely has a superiority complex(?) I empathize him but that doesn't necessarily means whatever he did to suha was right... But then if the possibility of him never being shown what is right or wrong.. is it really just his fault? At least he never forced suha on something... But was an asshole for it. I pity him .. ╥﹏╥