Eclipse of Fate. The Lunar Prophecy Series, #2

Where immortal beasts rule the mystical kingdoms of darkness and light, only true love has the power to change fate. Forbidden love ignites an ancient prophecy in this epic fantasy adventure. When werewolf alpha Cole and amnesiac witch Violet fall in love, they unwillingly fulfill a foretelling that their union will defeat a great evil. Joined by vampire Cassius, who has fought this same foe alongside Violet in previous lifetimes, the trio embarks on a dangerous quest to recover Violet's lost memories. Only by rediscovering her full magical powers can Violet reclaim her destiny as savior of the supernatural world of Evernite.
Cassius, Cole, and Violet must race to unlock the secrets of Violet's past and gather allies before otherworldly forces plunge their land into chaos. Bound by fate and their blossoming romance, Violet and Cole find their improbable affections could decide the future of realms human and magical alike. But grave revelations and betrayals await that will test the prophecy's champions like never before.