Holly and Oak - J.L. O'Faolain
There’s relationship backstory the reader isn’t offered, so rather than romance, I’d say this is a book whose strength lies in the intrigue of its mythology, with a little love to warm things up just before it ends.

See the entire 2.5 star review at The Novel Approach: http://thenovelapproachreviews.com/2013/12/20/holly-and-oak-is-a-big-story-in-a-small-package/