When the Tudor king Henry VIII fell for a young lady-in-waiting, Anne Boleyn, (who he described as having eyes "black and beautiful"), he was already married to a Spanish princess. But Anne refused to be a royal mistress, and so the king changed the course of history by getting a divorce through the Catholic church and making Anne queen.
In one letter to her he wrote, "I beg to know expressly your intention touching the love between us…having been more than a year wounded by the dart of love, and not yet sure whether I shall fail or find a place in your affection."
Their marriage ended when he had her beheaded.