You got into a fight with someone and it was a girl, the reason why you fought with her is because she was hitting and flirting on heeseung which is your boyfriend. And you couldn't just let it slide so you decided to confront her but then she got violent so did you.

skip

you came home and heeseung saw you with wounds and bloods and he hurriedly rushed to you "What the hell happened?!" heeseung said worriedly