James Buchanan is the only U.S. president who never married.
This does not mean, however, that he did not ever come close! In 1819, at the age of 28, Buchanan became engaged to Anne C. Coleman, the daughter of a Pennsylvania iron magnate. He eventually called it off for undisclosed reasons and his former fiancée died soon afterward, possibly a suicide. During his early political career, Buchanan lived with Senator William R. King of Alabama, a fellow bachelor and the future vice president to his presidential predecessor, Franklin Pierce. This caused a great deal of speculation about Buchanan’s purported sexuality, which continues to this day.
But who served as his First Lady when he was in office, you ask? That’s a good question. Buchanan did actually have a female relative who was able to fill this position admirably. This woman was his niece, Harriet Lane, who had been under Buchanan’s guardianship since she was 12 years old. At that time, her mother (Buchanan’s sister) had died, leaving her orphaned. Fifteen years later, she was the natural selection for Buchanan’s first lady, having traveled with him when he was an ambassador to Great Britain. Lane was so popular in this role that she earned herself the nickname of the “Democratic Queen!”