Prince Charles made secret phone calls to Camilla Parker Bowles during their family trips and Princess Diana was aware of it.

Many believe that the Prince of Wales never gets over Camilla even after marrying Princess Diana. In fact, he had private conversations with the Duchess of Cornwall and according to Princess Diana's former royal security Ken Wharfe, the late Princess of Wales was aware of it.

"It was sad in a sense for Diana of course because Camilla was always on the back of her mind," Wharfe said in "Robert Jobson's Royal Podcast" (via Express). "At one point during this trip, Diana was aware that Charles was on the telephone to Camilla."

Wharfe added that it was "besides the point" because those phone calls were something they "live with." Following Princess Diana and Prince Charles' split, the former said that their marriage was difficult as "there were three of us" implying about the Prince of Wales affair with Camilla.

Queen Elizabeth II and Prince Philip were not happy that Prince Charles and Princess Diana's marriage didn't work and they blamed their own son. According to royal biographer Robert Lacey, "It would be a great mistake to say [the Queen] blamed Diana for what went wrong."

"If anything, I believe, that she and her husband Prince Philip put more of the blame on Prince Charles, and Prince Charles of course, as we since discovered, was already committed emotionally to another woman," Lacey explained.

In addition, the Queen was reportedly aware of what Princess Diana went through while she was still married to the future king. In fact, she would see the Queen after the monarch finished her appointment and cry.

"Then she'd dash in before the next one, and just cry. She'd say 'everybody hates me, I hate my sister, I hate my mother, I hate my husband', and the Queen – not used to this type of moral confrontation – just didn't know how to handle Diana," royal correspondent Ingrid Seward said.

Prince Philip also preferred Princess Diana over Camilla for Prince Charles. In fact, in one letter addressed to the People's Princess, the Duke of Edinburgh called Prince Charles "silly" for leaving Prince William and Prince Harry's mom for Camilla.