Ten Thousand Skies Above You By Claudia Gray

Marguerite has no choice but to search for each splinter of Paul’s soul. The hunt sends her racing through a war-torn San Francisco, the criminal underworld of New York City, and a glittering Paris where another Marguerite hides a shocking secret. Each world brings Marguerite one step closer to rescuing Paul. But with each trial she faces, she begins to question the destiny she thought they shared.