The story of the blonde girl at the beach in the cartoon could be anything from her facing a challenge related to the ocean, to having a heartwarming encounter with another beachgoer. It all depends on the creator's imagination!
Another example could be Cinderella, in some versions she is depicted as a blonde. She endures hardships at the hands of her stepmother and stepsisters but eventually gets to go to the ball and find her prince.
A less well - known but still relevant YA novel could be 'Since You've Been Gone'. The cover might not be exactly as described, but the story of friendship and self - discovery in a young adult's life could potentially have a cover with a blonde girl. The grey background could be used to represent the emptiness or change that the main character experiences during the story.
The grey background can give a sense of mystery or melancholy, which is often found in YA novels. The blonde girl then becomes a focal point. It might make the reader wonder about her story. Is she a hero? Is she in a difficult situation? It creates intrigue. Also, the blonde hair can symbolize a certain kind of innocence or purity, which is a common theme in YA literature. So it gives an immediate visual cue about the possible themes in the book.