The Sky is Everywhere by Jandy Nelson

Lennie is devastated after the sudden death of her older sister. Her entire life she'd been the companion pony to Bailey's racehorse personality and now left on her own, Lennie isn't sure about her place in the world. When two very different guys become a part of Lennie's life, she has to deal with her overwhelming grief, understanding who she is, and the guilt she feels about finding happiness after Bailey's death.

Intermixed with Lennie's stunning poetry, a great cast of supporting characters, and beautiful and lyrical language, The Sky is Everywhere is a gripping story of grief and first love.