Forever by Maggie Stiefvater

"It was the knowledge that I was surrounded by adults with lives that I could never imagine living. It was the humming noise inside me that told me to do SOMETHING and found nothing to do that meant anything, the bit of me that was like a fly smashing itself again and again on a windowpane. It was the futility of aging. It was a piano piece gotten right the first time... It was roads that ended in cul-de-sacs and careers that ended with desks and songs screamed in a gymnasium at night. It was the realization that this was life, and I didn't belong here."