Marguerite was another Medici with an unhappy marriage. Her mother-in-law, Vittoria della Rovere, also had an unhappy marriage. Her mother, Marguerite of Lorraine, had a happy marriage with Gaston d'Orléans in spite of substantial meddling by Cardinal Richelieu. She was sent to a convent that she attempted to burn down and had several affairs while there. She was not supposed to leave the convent, but went to Versailles where she indulged in gambling. Her daughter Anna Maria Luisa was the last royal Medici potential heir-heiress. Her Wikipedia article is here.