Princess Diana reportedly wept during her final moments with Prince Charles before the latter flew to Australia and New Zealand for his royal tour. Instead of spending the final minutes with her husband, the Princess of Wales felt that Camilla Parker Bowles got in her way.

In the book “Charles: A Biography,” royal author Anthony Holden detailed the incident that reportedly broke Princess Diana’s heart even before she married the heir to the throne. Before Prince Charles left the Palace, the mom of two arrived to bid her boyfriend farewell.

But in a shocking twist, Camilla phoned Prince Charles to say her own goodbyes to the dad of two. Since Prince Charles was on the phone with Camilla for a few minutes, Princess Diana felt obliged to leave the room. At that time, though, Princess Diana was the official girlfriend of Prince Charles.

“She [Princess Diana] was weeping because her last minutes alone with the prince at the Palace had been interrupted by a phone call,” Holden said. “It was Camilla, wanting her own fond farewell. So tender was the conversation that Diana had felt obliged to leave,” he added.

Ten years later, Princess Diana revealed that the tragic moment really broke her heart. And according to Holden, it was one of the many things that the late royal struggled to recover from.

Throughout Prince Charles and Princess Diana’s marriage, Camilla was very much a part of their lives and not because the Princess of Wales wanted her there. The Duke and Duchess of Cornwall were having an affair while the former was married to Prince William and Prince Harry’s mom.

And during one of their heated confrontations at a party, Princess Diana asked Camilla to leave her husband alone. But the Duchess of Cornwall said that Princess Diana already had two sons and all the men wanted to be with her so what more could she possibly want. Princess Diana told Camilla that she wants her husband back.

“I do know what is going on,” Princess Diana told Camilla. “Don’t treat me like an idiot.”

Prince Charles and Princess Diana Prince Charles and Princess Diana on their last official trip together - a visit to the Republic of Korea (South Korea). Photo by Tim Graham/Getty Images