Enchanted

When their father, the Duke of Northallerton, offers his daughter Caroline's hand in marriage to his neighbour, the Duke of Lynchester, purely as a means of settling once and for all an ancient land dispute, she is appalled.
Not only because she does not love the Duke but also because she is already madly in love with another, the charming and handsome Edward Dalkirk.
Desperate to help her older sister, the aptly named young 'elfin' beauty, Lady Elfa Allerton, secretly waylays the Duke of Lynchester in his chaise and begs him to marry her instead and to leave her sister free for the man who she truly loves and adores.
Elfa from her childhood is fascinated by woods and goes to a wood to talk to the trees and immerses herself in the magic all around her and in times of difficulty she prays to the God of trees, Sylvanos, for his help and guidance and he always helps her.
Something about this young woman, Elfa, fascinates the Duke and reluctantly he agrees to do as she asks of him.
And despite the constant attentions of Society beauty, Isobel, the Countess of Walshingham, who is determined to keep him for herself, the Duke finds himself becoming enchanted by Elfa's quiet intelligence, innocence and beauty — just as she is spellbound by him.