The gravity between us / Kristen Zimmer.

Enhanced descriptions from Syndetics:

The Gravity Between Us is a daring, romantic, emotional story about friendship, love, and finding the courage to be yourself in a crazy world. New Adult novel: recommended for 17] due to mature themes and sexual content. "It's like there's gravity between us, like she's the only thing anchoring me to the world, keeping me from floating off into the upper stratosphere and being lost in space. I can't risk losing her." Where does friendship stop and love begin? At just 19, Kendall Bettencourt is Hollywood's hottest young starlet with the world at her feet - but behind the glamour and designer dresses is a girl who longs for normal. Payton Taylor is Kendall's best friend since childhood, and the one person who reminds her of who she really is - her refuge from the craziness of celebrity life. With her career taking off, Kendall moves Payton to LA to help keep her sane. But Payton is hiding a secret that could make everything ten times worse. Because to her, Kendall is more than a best friend - she is the only girl that she has ever loved. Just as they need each other more than ever, they'll have to answer the question of where friendship stops and love begins? And find out whether the feelings they have can survive the mounting pressure of fame...