It was supposed to be one of the most romantic moments of her life. But Princess Diana didn't see it that way. The late Princess of Wales admitted in recordings shared with biographer Andrew Morton for his bestselling 1992 book Diana: Her True Story that she initially thought King Charles III's marriage proposal was a "joke." At the time, the pair barely knew each other, having spent time together on only a handful of occasions during a six-month courtship, which made the sudden seriousness of Charles' question all the more surreal, InStyle.