It's korean so I don't know the WHYs but both the ML and 2nd ML suck each other's dick while the MC watches and seems like he is enjoying the view, but the 2nd MLs mind is full of him and MCs past seems like he is just drank?? Idk, I'm not just into throuples if that's what the Author wants
Saw the raw of Chapter 22 and no, not my cup of tea but MC seems to like it so okay