Wonwoo is the dark, while Mingyu is the light

Wonwoo is the night, while Mingyu is the day

Wonwoo is the yin, and Mingyu is the yang

Wonwoo's mind filled with negativity, while Mingyu's mind filled with positivity

Wonwoo had it hard, and so do Mingyu

But they react to their hard time differently

Wonwoo is the pesimist,

while Mingyu is the optimist

When both of them meet by fate, Wonwoo knows that he doesn't deserve someone as kind as Mingyu inside his life.

So all he does to him is push him away, as far as possible.

But he does regret it.

Because he knows he actually needs Mingyu.