SPOLIERS:
I can't fully remember but I think the look a like is a guy who became friends with ML and the white haired guy when they were in middle school? (If I remember correctly). He just happens to look kind of similar to Bae Jaewon (MC).
I read the novel and basically the friend that looks like MC ended up becoming extremely sick. The white haired guy really liked him, but I think MC just treated him as a friend. (Back then white haired guy and ML were good friends). So when the look a like became sick he was hospitalized for treatment but there was no hope (he was basically dying).
He was still getting like treated to prolong his life for as long as he could, he was doing this because the white haired guy was basically begging him to stay alive (he would stay by his side 24/7). But the look a like was basically like a shell of himself (he was really sick). So he calls ML one day and asks him for a favour. The favour is he basically wants ML to pull the plug while he's still lucid. Which ML does. But white haired guy finds out and calls ML a murderer cause of that. (I hope this makes sense LMAO).

Hi! I saw the raws but I don’t understand korean, and only seeing the images is not enough. Can someone spoil me? Who is the look alike? I kinda understood that white haired was obsessed (or in love) with him, and the relation with ML looked unilateral (to ML he was only a friend, but the lookalike liked the ML¿?). And the fact that ML killed someone is just a missunderstanding by white haired. Correct me if I’m wrong, this what I got just watching the images.