Prince William and Kate Middleton appear to have the ultimate fairy tale romance but just five years ago, William dumped his loyal girlfriend so he could spend more time clubbing with his friends.
Now, British author Penny Junor has revealed why William ended his relationship with Kate and what sent him running back in her controversial new book Prince William: Born to be King.
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Junor says the 2007 break-up was entirely William's decision, brought on by his fears that monogamy was impossible.
"The problem was William: he had very real worries about whether it was possible to love just one woman," Junor writes.
"After his hurricane childhood, he was understandably cautious about committing to a relationship.
"In his early years, he'd also lost many people he was close to. Subconsciously, he may have been wary of allowing himself to become too attached to Kate, in case she too abandoned him."
At the time of the split, William was serving with the military in Dorset, while Kate was living in London.
The couple spent less and less time together. To Kate's dismay, William started coming to London on his days off to go clubbing with friends and returning to Dorset without even dropping in to see her.
"It's likely he was feeling a bit claustrophobic: after all, they'd been together since the age of 20 and Kate had always wanted rather more commitment than he was prepared to give.
"Nor were all his friends that keen on her: some thought she was a bit too sensible and serious, and that she disapproved of their wilder antics.
"Meanwhile, William was all too aware that he hadn't had any other serious relationship before meeting Kate."
So William ended their romance and Kate though reportedly devastated decided the only thing to do was party.
She went out with friends nearly every night, with the paparazzi capturing her every move. Even William couldn't ignore the newspaper stories about his beautiful ex and within months, he was back in her arms.
"What brought him running back, according to someone who knows him well, was jealousy," Junor writes.
"Although his girlfriend had been miserable, she hadn't sat moping at home but had hit the town night after night, wearing a brave face and a sexy dress.
"William is quite old-fashioned in his outlook, and he realised he couldn't bear the thought of her with another man. But it was another three-and-a-half years before he proposed.
"Unlike his father, who married Diana without getting to know her, William waited until he was utterly sure that the marriage would last."
William proposed in November 2010 and the couple married in London's Westminster Abbey in April the following year, becoming the Duke and Duchess of Cambridge.
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