You are Kwangmin's girlfriend for a couple of months. He really loves you and you do the same. 

But one day at school, while you were going to his class to go home with him, you saw him talking with other girls. You heard that girl is the queen of their class and every boy there falls for her. In addition, You heard the word "oppa...?"

The girl : oppa! how about this way?

and.. you also heard "Tonight 6:00 p.m"?

Kwangmin : are you free at about 6:00 p.m?

You felt a little jealous of them... and once you checked his face expression, he's smiling at her and you could see all 32 pieces of his teeth... He smiled like that before you but you considered that precious smile was only for you. But now, what you see is Kwangmin giving his sweetest smile to another pretty girl. 
You feel your anger is growing inside you heart. You decided to ignore them and left them alone.
But Kwangmin heard your the sound of foot steps and turned to look the way the sound came from and he saw your back. Although it's just your back, there's no difficulty to guess whose back it was. So,

Kwangmin : Oh! isn't it EunJeong?
The girl : ah! I think so... but what happened? 
Kwangmin : may be she saw us..?
The girl : oh! she will be angry. eottoke?
Kwangmin : I must go now! I've to explain what we are. Don’t forget to come my home at about 6:00 P.M. Get ready! okay?
The girl : okay. bye oppa! 

On your way...