I’m confused

Why do you think blonde hair is just sleeping/messing with people? He clearly likes the people he sleeps with. Black hair is the only one who was ever messing with people too obv. So now I'm confused when I wasn't before....

when you said black hair blue eyes I keep on thinking about those yu-gi-oh cards >.<

As much I understand, he was having a lot of one night stands after moving out from home to forget woojin and later when he was slowly over it he formed relationships with people he genuinely liked, like that ex.
And i think woojin only messed up that ex who was trying to marry ceo's daughter

Woojin forced Haegyeong into their relationship.

When he was walking down the street with the other guy and lied to him he knew Haegyeong was watching them (his excuse for why he lied is suspect since it's unlikely he all of a sudden cared what Haegyeong thought when, even just before, he didn't).

He forced the ex to break up with Haegyeong in the past because, as Woojin said, he hated the MC.

When he found out the reason Haegyeong left (Woojin's grandfather blackmailing Haegyeong's family) he laughed at the trauma it caused the MC (yes, Woojin was angry at his grandfather but he made it clear that was only because he, himself, was inconvenienced) and it wasn't like Woojin didn't know how his own family was, considering his uncle killed himself for similar reasons.

Those aren't even all the examples. So yes Woojin is definitely the one messing with people, especially Haegyeong.

Plus, while I now agree Haegyeong was indeed just sleeping with people (in order to get over Woojin), that isn't messing with them.

Because there is a new person that knows him every chapter. Plus the guy was like “oh so he’s messing with him too” they also called him a “man whore” so that’s why I said messing with a lot of people.

You watch yu-gi-oh? Not a lot of people know that anime cause it’s so old

welp, back in the days...