admonike:
why did Yumi break up with woong?
Several reasons but they all can be sum up as lack of communication. Like they may want to say something but they just keep it inside. In the webtoon, there are this 4 scenes where you see their relationship starting to get tiring, like Yumi wants to do something and Woong says something that implies he doesn't care. All this things just start to annoy both and Yumi suddenly says things are not working out and Woong doesn't even fight for her, he's just like: guess not. So Woong is the one who actually breaks things with her. He also keeps a lot of secrets from her (like his business going under).