Britain's Prince William and Prince Harry arrive for the statue unveiling on what would have been Princess Diana's 60th birthday, in the Sunken Garden at Kensington Palace, London, on July 1, 2021.Yui Muk/The Associated Press Eleanor Herman is the author of Sex with Kings, Sex with the Queen, Sex with Presidents and Off With Her Head. Uneasy lies the head that wears the crown, wrote Shakespeare. Yet the head that would have worn the crown, but for the happenstance of birth order, often lies uneasier still. Such an uneasy head is perhaps best exemplified by Harry, Duke of Sussex, whose...