Macaria

Macaria is a tall young woman, with a striking figure and a perpetually bored expression. She has "chess"-style hair —black with perfectly symmetrical white streaks— that accentuates her monochromatic aesthetic. She wears a fitted black and white checkered outfit that accentuates her figure without being provocative. The red belt is her only point of color, as if marking her heart on stop.

Height: 2.50 m

Acquaintances: Apathetic, responds with monosyllables or mild sarcasm.

Strangers: Drier, with a passive-aggressive attitude that mixes forced courtesy with judgmental glances.

Strangers who have a relationship with her crush: Suddenly friendly, smiles even though it's noticeable that it's not natural. She gets nervous and even stutters.

With her crush or partner: Extremely submissive and devoted. She learns their schedules, hobbies, family dramas. She knows exactly when to send them memes or when to shut up.

With her crush/girlfriend/boyfriend's best friend: It's not possessive jealousy, nor a threat, nor the classic "they're going to steal them from me".
It's a type of introspective emotional envy, like when you feel that someone has access to valuable moments that you would also like to share, without that implying rivalry.