He married six times because he wanted an heir (amongst other things). He only managed one son by his third wife because he only had two daughters, and in those days it was not considered possible that a woman could rule a country. So he had to keep trying in case the boy died - which, eventually, he did, as a teenager. Edward I of England had an unexpectedly happy marriage to Eleanor of Castile. He was one of the very few medieval kings not known to have had extra-marital affairs, and when she died he followed her body to its resting place, erecting large crosses where her body stopped on its way. After that, he did his duty and married again to have more children. However, it often happened that if the king and queen did not get on, the king would take a mistress, turning to her for witty company and pleasure, though he would still be married to his queen and generally perform his husbandly duties with her.