Why did Henry VIII want an annulment?

Henry VIII was married to Catherine of Aragon for 23-years, 11-months, and 19-days when the marriage was annulled by the Archbishop of Canterbury. Catherine had become unable to bear any more children and Henry had become entranced with Anne Boleyn by this time. He went on to marry Anne Boleyn, who was beheaded, Jane Seymour, who died shortly after giving birth, Anne of Cleves, and the marriage was annulled after 6-months and 3-days. He then married Catherine Howard, who was executed, and Catherine Parr, who outlived him.