The ending of the book was pretty catastrophic. A re-occurring theme throughout it is that disappointment is going to be around until literally the end of time.
Very big pieces of the puzzle in this book fall apart in the last 8 chapters. One of those pieces is Sylvia, her father's "friend" moves away, taking a heavy weight off of Julia's shoulders. Her grandfather, also a big piece of her life, is found dead in his basement after her and her parents drive all the way to Circadia to look for him. Another rather large piece of her life is her middle school crush, Seth Moreno has the syndrome, and he's been hiding it. Julia discovers it when he has a seizure with her, and then he just up and moves to Mexico. These forces motivate Julia to keep a level head and make sure she's in the right state of mind. She is very level-headed like her father, and thinks very logically throughout the book.