Princess Diana's former private secretary claims her relationship with Dodi Fayed would've "disintegrated".
Michael Gibbins isn't convinced the pair would've remained a couple for much longer if they had returned from Paris, France - where they tragically died in a car crash in August 1997 - despite previously speculation the pair were planning to marry.
He told The Sun newspaper: "I think frankly she was just having a lovely summer at somebody else's expense to be perfectly honest.
"When the summer was over, everything would have disintegrated."
Diana was a guest on the Fayed family yacht, The Jonikal, during her final month, and while Michael believes the late Princess of Wales had a great time on the vessel, he insists she was not going to wed Dodi.
When asked if she had mentioned marrying him, he replied: "Absolutely not. Nor do I believe that for a second.
"Superficially she was happy. Deep down, more difficult to say.
"She was a pretty complex person. Superficially yes, she enjoyed bobbing around on boats with Dodi Fayed. Who wouldn't?"
Michael believes Diana was "bitter and angry" about the way her marriage to Prince Charles - who she wed in 1981 but divorced in 1996 - had failed.
He added: "It was pretty upsetting for her.
"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."
Michael's claims come after priest Father Frank Gelli recently insisted Diana had asked him if she would be able to marry Dodi in a church, and he believes she may have been seeking Christian approval to tie the knot to the 42-year-old Muslim man.
He said: "She wanted to know if it was possible for two people of different religions to marry. I told her it was.
"As we spoke her telephone rang. It was obviously Dodi. Her eyes lit up. As she was leaving she asked me if I would be able to perform the service when she got married. Her love was obvious."
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