The Gate: The Immortal Coil Saga, Book 1

Amarynn, a legendary warrior who hates everything she's become, desperately wants her existence to end. But there's one problem with that. She's immortal.

Now, the only thing that can give her the ending she seeks has been stolen, and she must partner with the king’s son to make things right. If they fail, the wars between kingdoms will never end, and Amarynn will lose her desired ending. Though now that she's gotten close to Prince Jael, she doesn't know if that's a bad thing after all.