Symbolism, Imagery, Allegory
When we first meet Annabel (literally, on the first page), she's watching a TV commercial of herself. In it she's welcoming students back to school and showing off her fancy fake high school life. She's supposed to represent "the girl who has everything." Check it out:
"The girl who has everything," he'd said, moving his hands in a tight, circular motion, as if that was all it took to encompass something so vast, not to mention vague. Clearly, it meant having a megaphone, some smarts, and a big group of friends. Now, I might have dwelled on the explicit irony of this last one, but the on-screen me was already moving on. (1.8)
The commercial is just another representation of how everything is fine, perfectly fine with Annabel on the outside—she's a model with cool gigs, and she lives in a big pretty house. But inside she's dealing with a lot of problems—the world just doesn't see them. She only shows the perfect girl. When she sees screenshots from the commercial on the wall in Mallory's room, Annabel is struck by how false it all is:
No one's life was really like that, one glorious moment after another, especially mine. A real set of snapshots from my back-to-school experience would be something else entirely: Sophie's pretty mouth forming an ugly word, Will Cash smiling at me, me alone behind the building retching in the grass. This was the real truth about me going back to school. The story of my life. (11.52)
The commercial isn't the story of her life at all—it isn't the story of any real person's life. It's just a glossy aspirational version of what people think life should look like.