I still don't fully understand what's wrong with that guy. Does he want to be noticed by Sahoon? Is that why he's bothered by the fact they're dating? He probably wants to be closer with Sahoon and the fact that some girl, not even from their circle, has become so close with him, when he's trying so hard and there's no resultes, probably hit him hard lol
But using her friend...haaa, typical.
On a side note, Dayeon is the best! I like that she's so understanding.