An older sister of John Churchill, 1st Duke of Marlborough, she began her relationship with James, then Duke of York, around 1665, while he was still married to Anne Hyde. Arabella became the duchess's lady-in-waiting in that year, and gave birth to two children during Anne's lifetime. Their affair continued after James's marriage to Mary of Modena in 1673, and produced two more children. Some time after 1674, she married Charles Godfrey and had three more children.