John F. Kennedy Jr. refused to call Princes William and Harry following Princess Diana‘s tragic death – despite being urged to do so by his wife, Carolyn – because it was ‘too difficult for him,’ a new book has claimed.

In an upcoming biography titled, Once Upon A Time: The Captivating Life Of Carolyn Bessette-Kennedy, author Elizabeth Beller takes a deep dive into the life of the woman who stood alongside ‘America’s prince’ JFK Jr..

The explosive book promises to share the true identity behind the multi-faceted woman who had locked people in with her fiercely independent attitude as it lifts the lid on the other side of Carolyn that the public didn’t see – one that saw her begging her spouse to ring the royal brothers during a difficult time.

Elizabeth highlights Carolyn’s ‘compassion’ as she shares that she urged JFK Jr. to call Prince William and Prince Harry following their mother’s 1997 death, however, the attorney refused to pick up the phone because of Diana’s extremely public passing.

In an excerpt obtained by People, Elizabeth, whose book is set to be released on May 21, shared what transpired in the days after Princess Diana’s death.

The Princess died due to a fatal car crash during a high-speed chase by photographers in Paris.

Carolyn was furious about the Royal’s passing, especially because she had struggled with paparazzi herself.

Elizabeth wrote: ‘Carolyn tried to get John to call Princes William and Harry to give his condolences when it came out that Diana had hoped for her sons to emulate John’s modesty in the face of media obsession.’

However, JFK Jr. didn’t see the benefit of ringing the boys at first as he ‘didn’t know them and thought that their situations greatly differed.’

The excerpt read: ‘He had met [Princess Diana] once or twice, and the fact that she had died while being chased down by paparazzi, he was aware of the fact that their [he and Carolyn’s] lives were becoming overwrought with attention and he was upset.

‘Carolyn’s suggestion was lovely that he call them. He was, by all accounts, a lovely, gracious person, but maybe that moment was too difficult for him to be able to reach out and say something to someone who’s just lost their parent in a very public and dramatic way.’

The upcoming biography shows Carolyn – who died on July 16, 1999 – in a different light as she was previously described as ‘icy’ by headlines.

Carolyn died when a plane, being flown by JFK Jr. and also carrying her sister, Lauren, crashed into the waters off of Martha’s Vineyard.

Elizabeth revealed: ‘The press attention really terrified her. There was a vulnerability. And I think somehow the press attention and scrutiny just touched a nerve and it stole a lot of her joy.

‘She had a lot of compassion, and she was very caring and a good friend.’

Carolyn and JFK Jr. – the second child of US president John F. Kennedy and first lady Jacqueline Kennedy Onassis – started dating in the early 1990s, and they quickly became one of the most talked about couples on the globe.

Of course, the public already had an immense fascination with the Kennedys, but Carolyn’s bold fashion choices and her ability to turn even the simplest looks into a chic ensemble only drew people in even more.

Not only did Carolyn – who worked as the director of publicity for Calvin Klein’s flagship store in Manhattan – dominate the red carpet any time they attended an event, but she would also turn the New York City streets into her own personal catwalk when running errands or walking their dog.

Paparazzi would often camp outside of the couple’s New York City apartment in the hopes of catching a glimpse of them, and many became obsessed with seeing what she’d wear next.

And 25 years after the couple’s death, people around the world continue to praise the spouse of JFK Jr. for her envious fashion and stunning looks.