Ah Young met Sungyeol when they were just in Jr. High.  He liked her from the very beginning, but being the choding he is, never knew how to express it.  He just poked her, and got her attention by acting like a little kid.  Even tough it bugged Ah Young at first, she soon got used to it, and even enjoyed it.  She would resent the days that they didn't talk.  But that was 10 years ago.  It's all a distant memory until they meet again.