She's not bleeding, it's just symbolic. Her cutie mark represent her talent for magic but it also seems to represent her and her friends (1 big star and 5 small stars). So now that she's lost her friends, she's loosing her cutie mark... or something.
I would've added a silhouette of her closest friend somewhere behind her. He would have to be a gray shadow in the background, but it would at least signify that he's the only one who hadn't abandoned her at that point.