An Oceans Solitary Star by Red Jade Stephens

A lover's betrayal is as bittersweet as a heart cursed with the agony of loss in this fantasy romance.
The next heir to the Harpy Kingdom and an Oceanic Nymph are forbidden to fall in love. One's destiny is to sacrifice her heart to the darkness, and the other hides from her problems. They both tell stories of heartache and betrayal that lead to a bitter end.
Dive into the mythological and magical world of the other realms beyond the mundane world, where Fae and the higher deities exist along with the dark creatures, such as Demons, Harpys, and Werewolves.