Its about a girl named Suzy who has a crush to this guy (Myungsoo) every since high school but don't have confidence to tell to the guy what she feel. 3 year after, she found out that Myunsoo already have a girlfriend and now are about to get married. She didn't accept it. She decided to create a plan to make them two broke up before the there wedding. 

Will her Evil plan works?

Or 

Would she just let them be happy and move on?