I know korean dramas love triangle can be annoying to the core. But this has to be worst of all. I think writter just wrote whatever he wanted without thinking twice. The way they build up female lead character is very poor.
She is confusing and unbearable at a time. They failed to build proper romance between her and male lead. It could have still worked but second male lead is annoying to the core. Everytime there is some good feeling, he ruins it.
So avoid it. Because its cliche korean story. Boyfriend cheat, then she meets two boys, then love triangle, then she chooses one, breakup with him later...