He is for sure you can see it crack when seunghyun mentions what if he says he doesn't care about the casino
ah, ok! but did he pretend the whole time? including the last scene where he said "blood"?
Oh no he's being all oh I love u I like u so much which is obviously true he does indeed love him but it's all antagonistic right now it's filled w venom he's like the yearner final boss only now is filled w hatred and seunghyun KNOWS that. Seunghyun KNOWS he hates him but isn't aware he actually loves him that's why he asks if he liked him back then and Yuta says I like you now. Right now Yuta is just trying to appeal to seunghyun so he pities him and starts falling for him. But no in the blood scene I'm pretty sure he's not pretending he's genuinely horrified that happened and seunghyun got hurt that badly.
He's partially pretending, he still loves Seunghyun (he was his first love and treated him well at Kinkaku) - look at his internal monologue in ch 8. The last scene from ch 24- he's not faking it, he is seriously mentally ill and Seunghyun is slowly getting that. That's why after shouting at Yuta and seeing his expression (genuine fear) Seunghyun's behaviour and tone change and he tells Yuta to stand still.
I need characters analysis! someone pls