Princess Diana only had a relationship with Dodi Fayed 'to have a fun summer on his yacht', it has been claimed.
Her private secretary Michael Gibbins said the romance was never real and would not have lasted.
The couple were killed in a car crash in Paris 20 years ago but Mr Gibbins believes their connection would have 'disintegrated'.
He told The Sun: 'I think frankly she was just having a lovely summer at somebody else's expense to be perfectly honest.'
The pair were pictured enjoying fun in the sun on Mr Fayed's boat and were even rumoured to have been shopping in Monte Carlo for an engagement ring, while others claimed she was pregnant with his child.
But Mr Gibbins said he 'absolutely did not believe' them and said her appearances on his yacht were because she 'superficially enjoyed' the lifestyle.
He told The Sun: 'My feeling was that she was determined to build a new her in whatever way. She was probably pretty bitter and angry at the way things had turned out.'
Meanwhile Mr Gibbins said he believes there is still 'much public resentment' towards the Duchess of Cornwall over the treatment of Diana and said there 'would be a riot' if she ever becomes Queen.
He added he was also against the young Princes William and Harry walking behind her coffin during her state funeral but felt it was not his place to voice his opposition.
The controversial issue has recently returned to the surface after Diana's brother Earl Spencer revealed he objected to the boys walking behind the procession and claims he was lied to after he was told they 'wanted to do it'.
It was recently revealed by one of the Queen’s most trusted aides how William and Harry were persuaded by their grandfather, Prince Philip, to follow behind their mother’s coffin on the eve of her funeral, saying: ‘I’ll walk if you walk.’
Sir Malcom Ross, the courtier responsible for planning the event, says the decision wasn’t made until the royals gathered for a ‘family supper’ hours before Princess Diana was laid to rest on September 6, 1997.
Mr Gibbins has been speaking publicly about Diana for the first time since giving evidence at her inquest after her death.
He added he was surprised the Royal Family did not leave their Balmoral residence after the death but 'understood they were trying to protect the boys'.
Mr Gibbins added: 'Maybe there was a lack of appreciation for the depth of feeling in London, which was quite extraordinary.'
Mr Gibbins said Diana would have been proud of her boys for speaking out about mental-health and attempting to modernise the Royal family.
He said some people believed it was not a sensible campaign for Diana’s two sons, but understood why they wanted to talk about their feelings.
And then described their father and grandfather as ‘very stiff upper lip’.
The Duke of Cambridge said in response: ‘There may be a time and a place for the ‘stiff upper lip’ — but not at the expense of your health.’
It comes after it was revealed Diana was heard opening up about her 'grim' marr¬iage split in a secret recording of a call with George Michael.
She told him the Royal Family was 'not very loving' in the chat about her divorce from Prince Charles.
As well as complaining about the pain of her bitter divorce battle with Prince Charles, she joined George in taking the mickey out of Sir Elton John.
Meanwhile her strong desire to help the poor was inspired by a visit to see Mother Theresa's home in Calcutta, newly discovered letters have shown.
After meeting with sick children in February 1992, the princess of Wales wrote a prayer and sent it to her butler Paul Burrell when she returned home.
An accompanying note said spoke of a profound awakening after praying with the nuns.
According to the Sunday Mirror, the note said: 'Today, something very profound touched my life. I went to Mother Teresa's home and found the direction I've been searching for all these years.
'The sisters sang to me, a deeply spiritual experience and I soared to such heights in my spirit. The light shone from within these ladies, saints for want of a better word, such love came from their eyes and their touch was full of warmth.'
Source: Daily Mail