She'd been enjoying a sun-dappled romance with Dodi Al Fayed but behind the scenes she was harbouring a secret heartache for another man.
On the last day of Diana, Princess of Wales' life, she woke up bobbing off the waters of Sardinia's famed Costa Smeralda.
On-board the Jonikal, the super yacht owned by Mohammed Al Fayed, the father of her boyfriend Dodi Al Fayed, not only the day but her future looked glittering.
She was enjoying the first public relationship since her divorce from Prince Charles the previous year and was riding high on the success of her global headline-grabbing anti-landmine campaign.
On that day – August 30, 1997 – sun-kissed and outwardly happy, Diana looked like she was finally, after the better part of two decades' of heartbreak and hurt, finding the happiness she had craved.
However, the truth is more complicated.
As Diana sunned herself on the deck on the Jonikal that summer she was nursing a broken heart, the relationship with the man widely held as the love of her life having ended.
Also, though freed from the bonds of being a royal wife, despite still having a Kensington Palace apartment and a title, despite having won $30 million in her divorce there were aspects of her future coming into focus and the view was less than pretty.
'ISN'T HE GORGEOUS?'
When Diana, the most photographed – and one of the most beautiful – women in the world met the man she would call "The One" on September 1, 1995 she failed to make much of an impact on him.
She was at the Royal Brompton hospital in London to support her friend, Oonagh Toffolo, an acupuncturist and self-described healer, after her husband had bad heart surgery. Into the room came one of the surgeons, a Pakistani-born man named Hasnat Khan, who was focused on the patient, not the glamorous woman in the room.
Later, Toffolo writing in The Mirror said, "It is doubtful if in her entire adult life Diana, the Princess of Wales, had ever made less of an impression on someone!"
But the slightly paunchy, mustachioed doctor had made a huge impression on the Princess. When he left the room Diana reportedly gushed, "Oonagh, isn't he drop-dead gorgeous? And his name is Hasnat Khan. It's written on his shoes."
Later, according to Vanity Fair, the unlikely couple found themselves in an elevator "and their eyes locked. 'I think I've met my Mr Wonderful,' she told Simone Simmons, her energy healer."
Diana and Hasnat's first date was about the furthest you could get from the chic restaurants that the royal frequented. In mid-September, he invited her to go for a drive to his aunt and uncle's house to pick up some books.
"I did not think for one minute that she would say yes, but I asked her if she would like to come with me," Hasnat told police years later. "I was very surprised when she said she would. After this, our friendship turned into a relationship."
The couple's relationship developed entirely behind closed doors, their clandestine romance remaining a secret for nearly a year. In her apartment at Kensington Palace, staff started to find ashtrays emptied in the bin and empty KFC packaging, despite the fact the princess neither smoked nor ate junk food.
According to reports, she would contentedly go to Khan's one-bedroom Chelsea apartment and busy herself ironing his shirts and vacuuming, revelling in these brief forays into the real world.
Life with Khan was a dramatic departure from the gilded life she was used to.
Khan, after her death, told police that "we once went to the pub together and Diana asked if she could order the drinks because she had never done so before. She really enjoyed the experience and chatted away happily to the barman."
This was not just some fling for either of them. The couple, Diana biographer Tina Brown has written, discussed marriage and children. However, there were a number of significant issues in their way.
The first was Khan's fears over having his life up-ended by the inevitable press onslaught that would follow if their romance became official.
And secondly, Khan's family was vehemently opposed to him marrying anyone other than a Pakistani Muslim woman of a similar social standing to their own elevated status.
Diana waged a stealthy campaign to woo the Khan family, twice travelling to Pakistan and meeting with his extended family. She became friends with Jemima Khan, the daughter of famed financier Jimmy Goldsmith who had married cricket legend Imran Khan and moved to Pakistan.
"Diana was madly in love with Hasnat Khan and wanted to marry him, even if that meant living in Pakistan," Khan has said, "and that's one of the reasons why we became friends.
"She came to visit me twice in Pakistan to help fundraise for Imran's hospital, but both times she also went to meet his family secretly to discuss the possibility of marriage to Hasnat. She wanted to know how hard it had been for me to adapt to life in Pakistan and she wanted advice on how to deal with Pakistani men and their cultural baggage."
Still, the princess' charm offensive failed to move her beau's conservative family.
Later, when their affair was finally made public, Khan's father said in an interview: "He is not going to marry her. We are looking for a bride for him."
By the summer of 1997, while Diana's post-divorce professional life was taking flight, her love life was falling apart.
Diana biographer Brown, who was friends with the royal, has written: "Hasnat Khan was slipping away. He didn't want to go public – which meant, in effect, that he didn't want to marry her. Hasnat couldn't face the onslaught of becoming Di's New Guy in every tabloid newspaper. He recoiled from the prospect of his work at the hospital being invaded by reporters.
"The friends of Diana with whom I spoke insist that she had broken off the relationship out of frustration that Hasnat wouldn't agree to marry, or even to go public.
"Love, or the lack of it, always dragged her down. With that descent came an emotion that never bedevilled her pioneering efforts on behalf of landmine victims or Aids patients: fear."
Of a home video of Diana with members of Khan's family that was aired on British TV, Patrick Jephson, her private secretary for seven years, has written: "I recognised the signs of a princess unhappy with herself and defiantly laughing to prove the opposite."
With her romance with "Mr Wonderful" on the rocks, Diana was distressed.
When Natalie Symons, her hairdresser, turned up at Kensington Palace around this time, she found the royal in tears. "I could tell she was totally distraught because she didn't have any mascara on, and she always puts her mascara on before she does anything else," Symons has said.
In July, she and her sons flew to the South of France to holiday at Mohammed Al Fayed's estate where the press photographed the trio roaring around on jet skis.
Several days after arriving there, Mohammed Al Fayed summoned his son Dodi from Paris to help entertain Diana.
When she returned to London, Khan felt like something was wrong.
During a meeting on July 27 at Battersea Park, "She was not her normal self, and she kept looking at her mobile phone," Hasnat later told police. "At the end of our meeting in Battersea Park, we arranged to see each other again, the following day, at Kensington Palace… It was at that second meeting that Diana told me that it was all over between us.
"I remember saying to her at the time, 'You are dead,' meaning her reputation was dead. I said this because I was sure that it was someone from Mohamed Al Fayed's group and that was how I felt about anyone involved with him."
On August 10, the first photos of Diana and Dodi kissing were published.
In early August, Diana flew to Greece for a cruise with her friend Rosa Monckton.
According to Brown: "During that trip, Diana told Monckton that the relationship with Hasnat was over … The two talked much more about Hasnat than they did Dodi, and Monckton firmly believes to this day that the relationship with Dodi was designed to make Hasnat jealous."
Jephson, writing in his book Shadows of a Princess, has said that "it has been persuasively argued that the whole show was intended to incite jealousy in Hasnat Khan".
Diana returned to London and then returned to the Mediterranean to cruise along the coast of Italy with Dodi.
By August 30, a flotilla of paparazzi were trailing in the Jonikal's wake, the global obsession with Diana's first public boyfriend reaching fever pitch.
Around 11.30am that day they left the boat, heading to a nearby airport to fly via private jet. Within 24 hours, they would both have tragically lost their lives.
It wasn't only Diana's romantic relationship that was floundering.
The Daily Mail's Richard Kay, or "Riccardo" as Diana called him, was one of the Princess confidants. He has said that by her final months, "the number of friends she had you could count on one hand."
She was on the outs with former great mates Elton John and Gianni Versace (though she would reconcile with John at the designer's funeral); gone was Simone Simmons and she was not speaking to her mother Frances Shand Kydd, who had developed a drinking problem.
SPIES AND BUGS
Burrell would later allege that Diana had written a letter in which she said she feared that Prince Charles was plotting to kill her. The former Kensington Palace staffer said that Diana had penned the letter in 1996 and had given it to him as "insurance."
In part it read: "This particular phase of my life is the most dangerous – my husband is planning 'an accident' in my car, brake failure and serious head injury in order to make the path clear for him to marry."
Friends of Diana, including Monckton, have cast doubt on the letter.
Still, there are other clues that Diana was increasingly fearful, including reportedly twice having her Kensington Palace apartment swept for listening devices.
She told one friend, according to Brown that, "I am a threat in their eyes. They only use me when they need me for official functions and then they drop me again in the darkness … They are not going to kill me by poisoning me or in a big plane, where others will get hurt. They will do it when I am in a small plane, in a car when I am driving, or in a helicopter."
The 36-year-old was also growing increasingly worried about her beloved sons. According to Kay, Diana told him: "Roberto, you are so naive. Don't you see, they took my HRH title and now they are slowly taking my kids? They are now letting me know when I can have the children."
Exacerbating Diana's unhappiness was the growing prominence of the woman she had dubbed "The rottweiler" in Charles' life, Camilla Parker Bowles. On July 17, he had hosted a 50th birthday celebration for his longtime love at Highgrove, the Wales' former marital home. Later, a positive TV documentary about Parker Bowles left Diana deeply upset.
"I feel terrible… so frightened and needy," she reportedly told her astrologer. '
CHAMPAGNE AND TEARS
On August 28, Diana and Dodi marked the first anniversary of her divorce from Charles with champagne. As they cruised around Sardinia, they shopped and lolled in the sunshine but by August 30, it was time for their summer idyll to end.
According to the Telegraph, Diana wanted to go straight back to the UK to see her sons however Dodi "insisted on a final flourish in Paris".
Not only did Mohammed Al Fayed own an apartment on the exclusive rue Arsene Houssaye but he also owned the fabled Ritz hotel.
At lunchtime on August 30, Diana and Dodi landed at an airport outside of Paris, and headed into the city centre, however from the moment they arrived they were set up on a tribe of photographers.
Philippe Dourneau, one of Al Fayed's chauffeurs, would later recall Dodi upset by the chasing paps and that he remembered Diana "screaming at him to 'slow down' so he would not hit a photographer."
When they arrived at the apartment, there were dozens of photographers waiting for them. The couple's final hours would seem dogged by a horde of press who chased them from one destination to another including when Dodi took Diana to see Villa Windsor, the Paris chateau where the Duke and Duchess of Windsor had lived and which his father owned.
Later it would be claimed that Dodi had shown the Princess the house with a view to them living there but, per the Telegraph, she told one journalist that afternoon that the house "has a history and ghosts of its own and I have no wish to follow that".
Their final night together would be marked by distress. Their initial plan to dine at Bistro Benoit was put paid to by the press mayhem.
Bodyguard Kes Wingfield has said: "As soon as their car moved off, the paps behaved like real devils. They called for their bikes and sped off like fools, trying to stick to the car. They could have knocked over pedestrians. People flattened themselves against walls as their bikes mounted the pavements and sped past."
Dodi nixed eating at Benoit, deciding instead they should head to the relative safety of The Ritz. At the hotel's L'Espadon restaurant they ordered, however, other diners would later say that Diana was crying. The couple is also said to have felt they were being stared at so headed upstairs to the property's Imperial Suite for their meal.
With the paparazzi staking out the front of the hotel, Dodi is said to have come up with the plan of tricking them by having the couple leave via the hotel's back door.
In images taken from security cameras in the Ritz, Dodi has his arm around Diana while she looks downcast. In one shot he tenderly rests his head against hers as they wait to run the press gauntlet.
Despite his plan, the snappers realised what was going on and gave chase.
At 12.18am on August 31, Diana, Dodi, bodyguard Trevor Rees-Jones and the hotel's head of security Henri Paul (who was behind the wheel) left the hotel. Five minutes later, the black Mercedes would slam into pillar 13 of the pont D'Alma tunnel.
While Diana and Rees Jones survived the crash, the princess was suffering from extensive internal injuries. At 4am she would be pronounced dead.
In one of the last photos of Diana she can be seen frantically looking out of the Mercedes' back window with a startled looking Paul caught in the photographers' flashes.
There is something so tremendously sad that in her final moments, having fought with such passion and strength to try and build the life she wanted, that she was still, eternally being hounded.
If Diana had lived she would have turned 59 years old in July and it's impossible not to wonder where she would be. Would she and Dodi have simply proved to be a summer fling? Would she and Hasnat Khan have reconciled and found a way to make their relationship work? Would Diana be living quietly in the South of France embracing peace and privacy or standing on the world stage?
Perhaps the only thing we can say for sure is that after a lifetime of fighting to find happiness and of fighting to find love and freedom, it would have been a life of her choosing. And that, that would have been her happily ever after, no prince required.