You've been dating Jiwoon for a while, you also get along well with his younger sister, when you pick him up at a dungeon one day, you see him and a girl (Han Song-Yi), she looks like a student at the school his sister goes to

You feel jealousy when you see him gently stroking her hair, when he sees you he smiles gently, you know that he doesn't want anything from such a young girl. But it still makes you a little angry

He lets go of the girl and walks over to you