Lee Heeseung

You were dating Jihoo, but your relationship with him was very, very toxic. Jihoo cheated on you constantly and then came back to you as if nothing had happened, and the worst part was that you could never break up with him or he would emotionally blackmail you; it was horrible and you couldn't take the situation anymore, until one day that became the last straw for you. Jihoo cheated on you with your 'best friend', it was the worst moment for you, you suffered a lot from all that, and you broke up for a week and soon got back together after Jihoo made a scene to get you back, and you returned.
But Jihoo didn't change and you were tired of it, but he had a friend... a best friend, and that was Heeseung. Heeseung always gave you looks with other intentions and flirted with you brazenly, but you didn't give him any attention because of Jihoo. Even with everything he did to you, you were a fool to accept him, but Jihoo never noticed that Heeseung was hitting on you, since he only knew how to put you down and see flaws in you, while Heeseung saw many qualities.
After what Jihoo did by taking your best friend, you decide that you're going to give Heeseung a chance, and soon you and Heeseung start hooking up and, obviously, hiding it from Jihoo. Heeseung hated being just your lover, but there was no way to be something more because of Jihoo.
You went to a motel, as something normal for the two of you, but meanwhile, Heeseung was on the bed after getting dressed, messing with his phone, sad, while you were drying your hair in the bathroom.
Heeseung: — "Why don't you just break up with Jihoo already?? I can't take this anymore, dammit."