Are your OCs shy about romance?
Alicia is a little bit, but her confidence seems to ebb in waves on any given day. She's not scared of or uncomfortable around Kattar at all, so some days she's confident and flirtatious and other days she wants to cover her face and avoid being looked at.
Kattar is in a similar vein to Alicia, shy some days and confident others. He's pretty good at faking confidence, but when something happens that shatters his facade he can actually be pretty shy and embarrassed. He's not great at expressing emotions, so this generally makes him uncomfortable, he'd rather wait for Alicia to express them, and then agree.
Kimberly isn't shy about romance, at least outwardly. Being romantic in and of itself doesn't make her uncomfortable, but she worries about making a bad impression, on someone new she likes, tho she fakes it until she makes it as best as she can.
Jinwoo feels awkward, but he doesn't express that very much, and so it comes off as being shy. Really, it's a bit more just unsure.