Myeah, might be turns out beneath her chill and superficial confidence she's insecure and wants to be adored, or values loyalty and reacts to shadiness or competition like that a bit badly. I def hope we'll get more depth and sides to her.
Actually, it's even possible imo she'll be paired with Tom, depending on how she'll be developed. Nefcy seems to have thought about Tom a lot, him inheriting the anger from his anger demon dad, not wanting that to define him, seeking therapy to overcome his mental issues, the vulnerability and loneliness and people only seeing the external angry demon prince shell and not the boyband-loving vidya-playing bro inside.
Tom still pursues Star, but they're not that great together, she pushes him on edge. I think he's already getting over her, but his dev arc needs him to break out from the loneliness.
He's got great chemistry with Marco, who calms him down, but he's clearly romantic, into big sweeping gestures, wants a gf. Jackie, chill and kind and supportive yet fun, could be a good fit. There's something about them both being named Thomas, having piercings, vague sk8r aesthetic, into Love Sentence. Star and Marco complement each other with their strengths and weaknesses, and depending on how Jackie will get developed they might similarly balance each other out, Tom's all fiery passion, too much so, and Jackie's chill and calm and steady, maybe too much so, and would benefit from some confident, devoted courting, esp if she gets dumped. She got really starry-eyed from Marco's kiss, so she's into romance, too.
Or maybe they'll just leave her single and she'll get ferguson'd, but she seems too cool to deserve that. I kinda hope something will turn out to be up with the sea theme, it's high time for her to get a proper personality and back-story.