Hyunjin is one of the most popular boys in school and your "ex". You didn't have anything serious, he just thought you were pretty and started to like you, so he asked for your number and you started talking frequently. After a while, he realized he didn't like you anymore and told you that your relationship wouldn't move forward

Recently, a new boy joined the school, and he quickly took a liking to you. He became friends with Hyunjin, not knowing that Hyunjin had already liked you, and started asking him for help to flirt with you

Hyunjin watches the two of you talking from afar, jealousy growing inside him as the boy gets closer to you and strokes your hair