While the Duke and Duchess of Cambridge are now the picture of wedded bliss with three adorable children, many people forget they once broke up.
In 2007, the couple split for a few months after six years of dating.
It was reportedly William who ended the relationship in April that year, after his father Prince Charles told him 25 was too young to settle down, and that it was "unfair to string Kate along".
But in a new book Kate: The Future Queen, royal expert Katie Nicholl claims not long after following his father's advice, William realised he'd made a mistake and went about trying to win Middleton back.
The Sun reports that, according to Nicholl, William met up with Kate a month after the break up to "plead" with her to get back together with him.
"They secretly met up at Clarence House and at a pub close to Highgrove, where William told her he wanted to get back together," she writes.
"Kate didn't want to rush anything. She had been badly hurt and told William she needed some time."
In June 2007, William invited Kate to a "Freakin' Naughty" themed costume party at his army barracks in Dorset.
Kate, agreed to attend - and went all out on her costume: "She was dressed as a nurse - a rather sexy one in fishnet tights and a short dress," says Nicholl.
At the party William reportedly "followed her around like a lost puppy" and the two "couldn't keep their hands off each other".
By the end of the night, they were back together and became engaged in 2010.
"At the time I wasn't very happy about it but actually it made me a stronger person," Kate went on to say of the breakup in their engagement interview.
"I really valued that time, for me as well, although I didn't think it at the time."