Joy by Danielle Steel

Allegra Dixon has never felt loved or wanted. Rejected by her mother - a cold, beautiful socialite - and her absentee military father, Allegra's only escape from her lonely existence is through books and her own rich fantasy world.
When she marries her childhood sweetheart, Shepherd Williams, it seems Allegra's life has finally taken a turn for the better. But as Shep is pulled into the dark world of military conflict, he is slowly destroyed by the horrors he has seen in combat, and becomes a dangerous man that Allegra doesn't recognize.
Desperate for a fresh start, Allegra leaves a job she loves in New York and moves to California to start a new life. She takes a job as assistant to film score composer Henry Platt, a man with a reputation for creative genius and an intense, frenetic personality.
As new opportunities arise and hard challenges continue to bar her path to happiness - can Allegra finally find the joy and fulfilment she truly deserves?