She married the Earl of Waldegrave in 1759. He died in 1763. Being illegitimate and non-royal, she secretly married the Duke of Gloucester, nephew of King George III. The Duchess of Devonshire's Gossip Guide to the Eighteenth Century ahd a good article about her here that states, "George threw a temper tantrum and tried to prove the marriage to be a farce but was defeated. The two were recognized but not welcomed at court, forcing them into exile onto the continent." Her Wikipedia article is here.