The Lady of the Rivers by Philippa Gregory
Jacquetta has heard the story of Melusina, a river goddess who fell in love with a human man, many times as a child. It is said her family is descended from Melusina, and that the eldest girl of each generation is blessed with some of Melusina's power. In Jacquetta's case it seems to be true: sometimes she can foresee. And while Jacquetta is a beautiful young woman from a powerful family in English-controlled France, it is her power that attracts the most powerful man in France: John, Duke of Bedford. But not all are as accepting of Jacquetta's unique gifts, especially when her friendship with the unpopular queen thrusts her into a prominent place at the English court.
The Lady of the Rivers (Book 3 in the Cousins' War series) by Phillipa Gregory is a story of romance and intrigue at the English court at the beginning of the Wars of the Roses, known then as the Cousins' War. Pick it up for the history, enjoy it for the magic, and read it again for characters.
View my suggested books by Phillipa Gregory