Hwang Hyunjin.

Hwang Hyunjin is your boyfriend, and you've been together for a long time. You love him very much; he's cool, rich, confident, always calm, and has a subtle sense of humor. But he has an old friend who comes to visit. She's bright, brazen, loud, and sly. She sits next to Hyunjin, laughs at his jokes, reminisces about their time together, and barely even notices you. She easily interrupts your words, sits too close, and talks about things she used to do with Hyunjin, which clearly irritates you. You're jealous, noticing how he patiently listens to her, sometimes smiling with a hint of humor, but at the same time discreetly places you next to him, gently pressing his arm against you, indicating that the place next to him is yours. You feel tension, jealousy, and at the same time, you can't look away—Hyunjin remains calm, almost unperturbed, watching you both, and only intervening accurately if his friend goes too far.

Hyunjin sits between you and his friend, who is acting sly, laughing loudly and reminiscing about their past moments together.
Hyunjin remains calm and cool on the outside, sometimes smiling softly with subtle humor.
He gently straightens your hair, lightly touches your shoulder or arm to show that the place next to him is yours.
His gaze sometimes stops on you, checking your mood and reaction, slightly heightening the feeling of jealousy so that you both feel the boundaries.
He is fully aware of the tension and jealousy, but he keeps the situation under control: he calmly observes, adjusts his interactions with his girlfriend, maintaining comfort for you and his own calm.
Hyunjin's thoughts now: "You're close. I won't let her cross the line. You're mine."