The biography Prince Charles: The Passions and Paradoxes of an Improbable Life reveal some unknown facts about the Kings’s life. According to the author, Sally Bedell Smith, Charles felt pressured to marry Princess Diana, a union with a well-known tragic end. At the time, King Charles was still in love with Camilla Parker-Bowles, his former girlfriend who had married someone else. Smith writes that the night before his wedding to Diana, Charles was devastated over his lost love, and wept over his broken dreams.
King Charles Felt Pressured to Marry Princess Diana
Charles and Camilla dated for two years after meeting in 1971. Bedell Smith writes that Charles was attracted to Camilla’s down-to-earth nature. She loved the countryside, disregarded fashion, and most importantly, she “always listened.” They also shared the same sense of humor. Lady Annabel Goldsmith explains that Camilla was “an intensely warm maternal laughing creature, with enormous sex appeal.”
Despite seeming to be happy together, they broke up when Charles went overseas with the Royal Navy in 1973. Patricia Mountbatten, the daughter of the late Lord Mountbatten tells the author that there were “obvious problems” with Charles having a relationship with Camilla. She “had a history,” which was code for her on-and-off-again sexual relationship with Andrew Parker-Bowles, who she eventually married. According to Mountbatten, “You didn’t want a past that hung about.”
Bedell Smith goes on to write that Charles and Camilla broke up when he was 24 and not yet ready to settle down. Soon after, Camilla made up with Parker-Bowles and they married in 1973. Charles was even named godfather to their first son, Thomas. But later on, Charles and Camilla’s relationship rekindled with an ongoing affair in about 1986.
In 1980, Charles began to date Diana and was met with pressure to marry her. They had a 13-year age gap, but on paper, Diana was a perfect princess candidate, beautiful, fun, aristocratic, and no “history”. King Charles still wasn’t in a hurry to settle down. Then the press began to speculate that the couple had spent two nights with each other, a claim Diana denied at the time. But according to Bedell Smith, this pushed them into wedlock.
Read: Harry Says Diana Was ‘Chased To Her Death While She Was In A Relationship With Someone That Wasn’t White’ And Feared ‘History Was Repeating Itself’ With Meghan
“He Wasn’t Ready”
Prince Phillip wrote a letter to Charles stating that Diana’s reputation is at stake and he must make a serious decision about their relationship. Bedell Smith says Charles understood this as an order to propose to Diana although he “wasn’t in love, he wasn’t ready. Psychologically he assumed his father bullied him, so he read it as a bullying letter.” Meanwhile, Bedell Smith read the letter as “Charles should either propose to her or release her. In either event, he should make a decision shortly.”
In any event, Charles and Diana got engaged in February 1981 and married that July. The cracks in their relationship had begun from the start. Bedell Smith explains that the two were very different personality-wise with different interests. 
Another royal author, Penny Junor, reports that Charles had begged Camilla not to go through with her marriage to Andrew. He lamented the shortness of “such a blissful, peaceful and mutually happy relationship”. Her book, The Duchess: Camilla Parker Bowles and the Love Affair That Rocked the Crown, claims that Andrew was unfaithful to Camilla, who forced him to turn a blind eye when her affair began with King Charles. However, after 20 years of marriage, Camilla and Andrew announced their divorce in 1995. Charles and Diana had already separated in 1992 before Diana’s tragic death in 1996. 
Read: Have You Ever Noticed This One Strange Detail in Pictures of Princess Diana and King Charles?
Charles and Camilla Get Back Together
Because of the public’s response to Diana and her death, Charles and Camilla tried to keep their re-re-kindled relationship a secret. But even the royal family was reluctant to accept Camilla. But in 1999 they were photographed as a couple together. Slowly, the family began to warm up to her, with William and Harry joining the couple on a trip to Greece and then the queen formally meeting Camilla in 2000. By 2003, the couple moved in together into Clarence House. Finally, in 2005, Camilla and Charles married in a small civil ceremony and remain together to this day. Their wedding was a sharp contrast to the lavish wedding of Charles and Diana, watched by 750 million people on the TV.
A month before their tenth anniversary, King Charles praised Camilla in an interview, saying, “It’s always marvelous to have somebody who, you know, you feel understands and wants to encourage. Although she certainly pokes fun if I get too serious about things. And all that helps.” 
- “Prince Charles Wept the Night Before His Wedding as He Felt ‘Pressured’ into Marrying Diana, New Book Claims.” People. Maria Mercedes Lara.March 20, 2017
- “Prince Charles cried before marrying Princess Diana and begged Camilla not to wed her husband, new book claims.” The Sun. Patrick Gysin, Emma Lake. September 16, 2019
- “A timeline of Prince Charles and Camilla, Duchess of Cornwall’s controversial, long-lasting relationship.” Insider. Lara Walsh. March 15, 2021