why did Igraine want she and her husband to leave the kingdom?

During his reign as King of all England, Uther Pendragon became embroiled in a long battle against the Duke of Tintagil (also called the Duke of Cornwall). It began when Uther one day sent for the Duke and his wife, the beautiful Igraine, to join him at his court. Uther welcomed them, but soon fell in love with Igraine and openly lusted after her. Igraine, loyal to her husband, begged him to escape with her in the middle of the night so that she would not be dishonored. They did so, but at the advice of his Barons, Uther sent a charge of men to summon them back to court. They refused. Uther, ever wrathful, told the Duke to prepare for war.