Ever by Gail Carson Levine

As with Levine's other books, Ever takes a fairytale and turns it on its head.

Kezi is a young girl living with her family. They are a devote family, praying to their god Admat and following his laws. But one day, Kezi's mother becomes sick. Kezi's father, in an attempt to cure his wife, promises to kill the first person who congratulates him on his wife's recovery in a sacrifice to Admat. In their world, an oath is no longer valid after three days, so after Kezi's mother becomes well, the family lives in fear as to who will congratulate her father.

Olus is a young god from another country, fascinated with humans. He has longed for a friend his whole life, but he never imagines he'd fall in love with Kezi. As he watches their life, he becomes more infatuated with her, even daring to introduce himself and save her at one point. When fate intervenes, Olus is determined the two of them can overcome destiny to write their own.

This tale is told in both Kezi and Olus' point of view. Each chapter alternates, but the story is powerful and amusing.