Prince Charles may be destined to become king, but that doesn’t mean the royal is confident about the choices he has made. According to a royal biographer, the Prince of Wales felt like a failure following his split with Princess Diana.

Although Charles tried to make his marriage with Diana work, the royal became hopeless and gave up on their relationship. His decision reportedly haunted him for years following their divorce.

A year before Princess Diana’s scandalous biography, “Diana: Her True Story” was released, Prince Charles stopped trying to save his marriage. In the book, “The Firm,” Penny Junor claimed Charles felt terrible he couldn’t make his marriage with Diana work.

“He gave up. Not because he didn’t care, but because he couldn’t help. He felt desperate, hopeless and guilty, and to this day he feels a terrible sense of failure for not having been able to make his marriage work,” Junor wrote.

Although the couple struggled, it didn’t mean they didn’t experience periods of joy. “That is not to say there was no happiness. There were moments of intense pleasure, the children brought huge joy, and there was laughter and jokes and fun, but not enough to counter the difficulties,” the royal biographer explained.

“As time went by, the gulf between them became no longer bridgeable,” she added.

Years later in her 2017 piece, “The Duchess,” Junor claimed Prince Charles became overwhelmed with guilt after Princess Diana’s death in 1997.

“He wept bitterly at the sheer tragedy of it all, that their life together, which they had both so wanted to work, should have ended in such acrimony and anger, and he wept for William and Harry. And he wept for his failure to help Diana,” she explained.

“He knew he had done his best – no guilt there – but she’d been beyond any help. It was a bruising and difficult time for him.”

Prince Charles and Princess Diana finalized their divorce in 1996. The Prince of Wales continued his relationship with Camilla Parker Bowles, and the two married in 2005. The wedding was attended by Charles and Diana’s sons, Prince William and Prince Harry.

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