For the King's Favor, by Elizabeth Chadwick, free in Canada, Australia and no doubt will catch up to US customers later (although UK customers seem to have been skipped on this one).
Book Description
A Bittersweet Tale of Love, Loss, and the Power of Royalty
When Roger Bigod arrives at King Henry II’s court to settle a bitter inheritance dispute, he becomes enchanted with Ida de Tosney, young mistress to the powerful king. A victim of Henry’s seduction and the mother of his son, Ida sees in Roger a chance to begin a new life. But Ida pays an agonizing price when she leaves the king, and as Roger’s importance grows and he gains an earldom, their marriage comes under increasing strain. Based on the true story of a royal mistress and the young lord she chose to marry, For the King’s Favor is Elizabeth Chadwick at her best.