The Earth Turd (Star vs the forces of evil)

I do NOT own the characters, the wand, or anything.

One day, Star and Marco are at school. Jackie (Lyn Thomas) flies by on her skateboard.
"Hey Marco! Uh, I was wondering if you want to hang out some time?" She asks, blushing. Marco replies:
"I'd love to!" Star begins to feel a bit of sadness and longing in her chest. What is this feeling? Is it what the humans call jealousy?