A change for the worst? (A kpop based fic!)

Description: Based on the Taiwanese drama, 'Hi! My sweetheart', where Jiyong is a nerd who falls head over heals for tough 'bad girl' Chaerin. But when a family problem arises and Chaerin has to flee to her family, leaving a misunderstanding behind her Jiyong is forced to believe that he has been betrayed by her and changes... For the worst? It also doesn't help that he is informed that she ran off with a man, who is extremely handsome and named Bang Yongguk.