Complex sentence: Her youngest sister Catherine of Aragon would become a widow after her teenage husband Arthur, Prince of Wales died in 1502 and she would be cast aside by her husband Henry VIII when she failed like four of his later wives to give him a male heir.
Split into simpler sentences: Her youngest sister Catherine of Aragon would become a widow after her teenage husband Arthur, Prince of Wales died in 1502. She would be cast aside by her husband Henry VIII when she failed to give him a male heir.