Although royal fans around the world tuned into Prince Charles and Princess Diana’s royal wedding in 1981, the couple’s marriage was far from the fairytale it was portrayed to be on television.

Toward the end of their marriage, the Princess of Wales began sharing intimate details about her marriage with the public, including Prince Charles’ affair with Camilla Parker Bowles. One royal author believes that Diana’s past behavior ruined her marriage and her role in the royal family.

READ: Why Prince William Can ‘Never’ Forgive The Way Queen Elizabeth Treated Princess Diana

In the book, “Charles: The man who will be King,” Howard Hodgson revealed that Prince Charles and Diana’s different childhoods may be the reason why the couple’s relationship fell apart.

“Unlike the Prince of Wales, Diana was also quick to bombard her parents with pleading letters saying how unhappy she was and begging them to take her away without delay,” he explained.

“The fact that they acquiesced after just one term is in stark contrast to the years of misery suffered by Charles at Gordonstoun and perhaps offers more than a little explanation to why, in her later role, she often lacked the discipline that her husband, and his family expected of her.”

Hodgson claimed that Diana became accustomed to getting her way if she threw a tantrum, whereas, Charles learned to adapt to the situations he was put into. After Diana failed her O-levels twice, she was sent to a finishing school in Switzerland called Institut Alpin Videmanette.

However, since the curriculum was taught in French, and Diana wasn’t fluent in the language, she didn’t thrive in her new environment. “The result was that she had difficulty fitting in socially and her classwork — which she had always found difficult enough in her native tongue — was now nothing short of pathetic,” Hodgson wrote.

While Charles unhappily remained enrolled at Gordonstoun, Princess Diana was able to convince her parents to allow her to move in with her mother. Frances Shand Kydd, in Knightsbridge.

Hodgson claimed their different upbringings caused the couple to clash later in life. Prince Charles and Princess Diana finalized their divorce in 1996.

Prince Charles and Princess Diana
Princess Diana and Prince Charles attend a welcome ceremony in Toronto at the beginning of their Canadian tour on Oct. 1, 1991. Getty Images/Jayne Fincher