The Wild Girl by Layne Mosler. The book is being released by Thomas Dunne Books on July 7, 2015.
Amazon says this about the book: One of six sisters, Dortchen Wild lives in the small German kingdom of Hesse-Cassel in the early 19th century. She finds herself irresistibly drawn to the boy next door, the handsome but very poor fairy tale scholar Wilhelm Grimm. It is a time of tyranny and terror. Napoleon Bonaparte wants to conquer all of Europe, and Hesse-Cassel is one of the first kingdoms to fall. Forced to live under oppressive French rule, Wilhelm and his brothers quietly rebel by preserving old half-forgotten tales that had once been told by the firesides of houses grand and small over the land.
As Dortchen tells Wilhelm some of the most powerful and compelling stories in what will one day become his and Jacob's famous fairy tale collection, their love blossoms. But Dortchen's father will not give his consent for them to marry and war, death, and poverty also conspire to keep the lovers apart. Yet Dortchen is determined to find a way.
Evocative and richly-detailed, Kate Forsyth's The Wild Girl masterfully captures one young woman's enduring faith in love and the power of storytelling.