Remember Me — Nina Croft

Unable to bear the thought of losing his mortal wife, Caden Wolfe steals the Elixir of Life and offers her eternity. But the theft is discovered, his wife is slain, and Caden is stripped of his angel wings and cast down into the Abyss.
Having drunk of the Elixir of Life, Phoebe Little's soul is tied to the earth in a perpetual cycle of death and rebirth. Unaware that she has lived countless lives, Phoebe is haunted by the loss of a love she has no memory of.
Caden has spent a thousand years searching for his wife. Now he has found her, and only Phoebe's love can redeem them both. But Phoebe fell in love with an angel, and Caden is now a demon of the Abyss. Can she see past what he has become, remember the love they once shared, and have a second chance at forever?