Heeseung was your boyfriend for 3 years. You and him were inseparable. So much to the point people thought you two will be married–long story short, it never happened. Because aside from having great chemistry, you and him fight because of... grade. Yes, you two may be lovers, but academic rivals at the same time. That fight was the very cause of your break up.

You were in the cafeteria, sitting at a table alone (it was your choice) when Heeseung approached you

"Haha, lonely I see."