Bro I feel so bad for Sieon it's true that what he did isn't correct but it's not his fault, I don't know about you but at least I felt that when he was giving advice to his sister it was so that she would understand Namwoo better and not take it in a bad way, I mean he even lied and did everything to make Namwoo feel calm and well and not be anxious so I think he did it for his own good too, but it's a shame that Namwoo didn't see it that way
been saying namwoo is the problem but everyone is so blinded by Sieons lack of emotions they keep painting him as the bad guy. Sieon has done nothing but make things comfortable for namwoo. Every time namwoo introduces him as some random person,sieon smiles and goes along. Every time Sieon lies its cause the situation would benefit Namwoo, this man is carefree and will alter his persona to fit Namwoo, the only thing he cant offer is dep romantic love.