Princess Diana's Fatal Mistake: Why She Left Luân Đôn for Paris with Dodi 

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Princess Diana\'s Fatal Mistake: Why She Left London for Paris with Dodi

Her divorce was finally behind her, and for the first time in ages, Princess Diana seemed to be hitting her stride.

It was the summer of 1997: At age 36, she was a world-renowned style icon and she had found deep personal fulfillment in a variety of causes close to her heart. And after years of personal anguish in her doomed marriage to Prince Charles, she seemed to have made

sort of peace with the fact that her ex-husband and the woman who helped break up their marriage, Camilla Parker-Bowles, had settled into domestic bliss. (Unabashedly so: The bliss included a lavish $45,000 birthday party present from Charles to Camilla that July.)

"Diana was starting a new life. She had said, I\'m spreading my wings.\' She was being quite positive about her divorce," royal biographer Judy Wade (

) tells PEOPLE. A 35-year-veteran royal photographer, who asked to speak anonymously, agrees: "Everything as far as her relationship with Charles, her great relations with the kids, that side of her life was in order."

"in order" was Diana\'s love life. Her relationship with distinguished Pakistani surgeon and cardiologist Hasnat Khan, a man many believe Diana had been in love with, had hit a rough patch in July. "She had wanted to marry him," says Wade. "She had this vision that together they could bridge east and west, crossing creeds and continents. They could save lives and make it a better world."

But Khan had rebuffed Diana. "They had a bust-up in July, and the romance was rocky," says Wade. "He didn\'t want to be a walker to a famous woman. When that broke up she felt her life was amiss, she was depressed."

Enter Mohamed Al Fayed, the controversial Egyptian business tycoon and then-owner of department store Harrods, who extended Diana an invitation to visit his villa in St. Tropez along with her sons, 15-year-old Prince William and 12-year-old Prince Harry.

She accepted, and the subsequent quiet arrival of Al Fayed\'s son Dodi, a 42-year-old playboy and minor film producer, set up a chain of events that no one could foresee.

Diana and Dodi began a discreet romance, with presents arriving at Kensington Palace such as "a huge box of tropical fruit, a roomful of pink roses, a Cartier panther watch," says Wade. "Dodi became Diana\'s distraction."

Princess Diana with Prince William on their last summer vacation

But in August, when Harry and William went up to Balmoral, the Queen\'s Scottish estate, to spend time with their father, Diana found herself alone. "I\'m sure she was missing the boys. She was at a loss in London," says Wade. "August is the time when anyone who is anyone leaves London." Besides, "Diana had alienated most of the friends she used to go on holiday with at that time of the year," adds Wade. "She used to drop friends for no apparent reason."

So it\'s perhaps no surprise that, in late August, when Diana got back from a trip to Bosnia for her landmine charity she let herself be wooed again by a man Wade describes as "kind-hearted and considerate, with a reputation for beautiful women."

Perhaps like Jackie Kennedy in the mid-\'60s, Diana thought she had found her own Aristotle Onassis. Or perhaps she was just being pragmatic. "Dodi had private jets and yachts at his disposal. St. Tropez in the summer is the haunt of the British paparazzi," says Wade. "Perhaps Diana wanted to be photographed frolicking with Dodi to make Hasnat pay for their recent rows."

Whatever the reason, there was little doubt in the minds of anyone who knew Diana well that the princess was having nothing more than a summer fling. "She would tell her hairstylist, \'I love his exotic accent! I love the way he says, \'

, you\'re so naughty!\'" recalls Wade. "But she told a confidante, \'I need marriage like a hole in the head.\' A close friend doubted that Dodi had replaced Hasnat [in Diana\'s affections] and was sure Diana and Hasnat would get back together in September."

Diana apparently heard the reports of Dodi having financial debts and having a weakness for cocaine, as well as the accusation from his ex-girlfriend that he\'d two-timed her and Diana. "The stories were not very complimentary," says Wade. "I think Dodi was a step too far for Diana," agrees the veteran royals photographer. "I think Diana enjoyed the excitement, but I don\'t think she could have coped with that [long term]."

Related Video: Royals Flashback: Prince Charles and Princess Diana\'s 1981 Wedding

Furthermore, whether the financial impropriety and drug rumors were true or not, everyone agreed that Diana wouldn\'t have done anything that would have jeopardized her life with her two young boys in any way. "After knowing Dodi only six weeks, that wasn\'t enough time for her to decide. The boys were her priority, and she would have consulted them," says Wade. "She would have asked herself, \'Is Dodi a suitable stepfather for my children?\' And she would have thought he wasn\'t."

On what was to be the couple\'s last day together, after they had cut short their visit to Sardinia to fly up to Paris – possibly to escape the omnipresent paparazzi – they visited the old home of the Duke and Duchess of Windsor, now owned by Mohamed Al Fayed. On the way there they were chased by paparazzi and, according to Wade – who spoke to one of Al Fayed\'s bodyguards for her book – Dodi ordered the driver to speed up to get away from them.

"Diana and Dodi had a violent disagreement," says Wade. "Diana begged Dodi to slow down. By the time she arrived at the villa, it was obvious she was upset. She was crying and had been genuinely frightened for her own safety and that of the paparazzi. It was a chilling portent of what would happen later on that night."

Perhaps for that reason, Diana didn\'t spend a lot of time looking at the house that Al Fayed Sr. had said the couple could live in if they married. According to bodyguard Philippe Dourneau, "Diana didn\'t [even] venture upstairs," says Wade. "She seemed to want to get away. They didn\'t hold hands. They seemed like acquaintances."

From there the couple returned to Paris on the afternoon of August 30, and by then, a chain had long since been set in motion. Its tragic culmination in the early-morning hours of August 31 – involving aggressive paparazzi, a drunk driver far over the speed limit, a tunnel in Paris, a playboy and a princess – would shock the entire world and impact the British monarchy irreparably.

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