Today they seem rock solid: loving parents of three young children and a couple whose loving warmth is plain for all to see.
Few romances have been as retold as that between William and Kate and their meeting at St. Andrews University on the Fife coast.
Yet both the Prince and Princess of Wales have, in a modest way, a ‘past’.
In particular, it is often forgotten that Catherine endured a brief relationship and early heartbreak at Marlborough College, her £46,995-a-year boarding school, and in the months that followed.
Pictured: Kate Middleton, left, with a friend at Marlborough College, in 2000
Kate’s first boyfriend, Harry Blakelock, was in the year above her at Marlborough School and left her heartbroken after their break-up
The couple met while studying at Marlborough College, Kate’s £46,995-a-year boarding school in Wiltshire.
The summer before she packed up her Prince Charming, Kate still longed for Harry Blakelock, her schoolgirl’s first love, during a three-month trip to Florence.
According to The Mail on Sunday, the Princess of Wales was still clinging to rugby captain Blakelock, although their long-standing relationship had gone ‘hot and cold’.
Harry had reportedly broken up with Kate ahead of his gap year to travel the world.
At the time, Kate was said to remain hopeful that she would get back with her ex and gave up her place at the University of Edinburgh in 2000 to take a gap year in Italy.
A friend of the princess told The Mail earlier on Sunday: ‘When Kate arrived in Florence she was really excited about Harry. She talked about him all the time and he seemed to have her quite confused.
‘It seemed he had been hot and cold with her when they were at school and she was always talking about how she could get him back.
“He was also in Florence at the same time, but as far as I can remember nothing happened.”
“Despite attracting men’s attention, she was always very shy around boys,” the friend added.
While in Florence, Kate shared an apartment with four other girls and enjoyed the freedom to roam unencumbered.
When she wasn’t photographing the cathedral and other Renaissance treasures, Kate spent her time studying Italian and art history at the British Institute of Florence.
Kate’s parents, Carole and Michael Middleton, visited their daughter during her stay in Italy.
A friend on her course said: ‘Carole teased Kate about an Italian waiter and said, ‘Isn’t he handsome?’ She tried to get Kate to take an interest in boys, saying things like, “Let’s buy you nice clothes, honey.”
But romance did not strike.
But later in her gap year, while working on the BT Global Challenge yacht in Southampton, she met fellow sailor Ian Henry.
Pictured: The future Princess of Wales, far right, with friends at Marlborough College in 1998. Left to right: Ruth Currie, Meryl Lawry-White, Gemma Williamson, Rebecca James and Kate
Kate, with the ball, plays hockey at Marlborough College in 2000. Her sister, Pippa, stands just outside her
A fellow crewmate said: ‘Everyone called her Fit Kate and the boys were very jealous when she got together with Ian.
“It was a summer romance, nothing serious, and it ended when they went their separate ways and went to college.”
When Kate returned from her gap year, she went to St Andrews University to study art history, although she initially secured a place in Edinburgh.
Some like to believe that Carole Middleton persuaded her to transfer from Edinburgh when she discovered William’s destination: St. Andrews.
Her A grades were exactly the grades needed to get a place at both universities to study art history, but a friend from that period says: ‘She just changed her mind.
‘A lot of her friends went to St Andrews. Traditionally it attracts large crowds from Marlborough. To anyone who actually knows Kate, the idea that this was all part of a grand plan is ridiculous.”
Kate and William met during their first year at university in 2001 – and famously caught the young prince’s eye at a charity fashion show in the spring of their first year at university.
During their 2009 engagement interview, Kate recalled feeling embarrassed when she first met her future husband.
She said: ‘I turned all red when I met you and walked away because I felt very shy about meeting you.
‘William wasn’t there for a lot of the time initially, he wasn’t there for Fresher’s Week, so it took a while for us to get to know each other, but we became very good friends from very early on.’
Kate and Prince William pictured on their graduation day at St. Andrews in 2005
Harry Blakelock and Felicity Thornhill pictured in New York in 2010
Although the couple never resumed their relationship, Harry eventually married one of Kate’s friends from school, Sarah Follett.
There is clearly no hard feeling – on the contrary. Kate invited him to her wedding to William in April 2011.
Today the University of Exeter graduate is a partner at Lockton, the world’s largest independent insurance broker.