Fifteen years since their fairytale wedding, the Prince and Princess of Wales' relationship is rock-solid.
With three healthy, happy children, and having successfully navigated the past decade and a half in the spotlight, William and Kate are stronger together than ever.
But in just a few short months, their family dynamic will change as they wave Prince George off to boarding school, marking a new chapter in their love story and no doubt a shift in their relationship too.
Their eldest son is on the cusp of becoming a teenager and embracing the independence that brings. When he begins his secondary education in September, this new phase may well give William and Kate the first inkling of what an empty nest might feel like in years to come.
© Getty"George going to secondary school will be an emotional time for them. It's a chance for him to spread his wings and take part in things in the afternoons and evenings instead of going home to Mum and Dad," says the royal author Robert Jobson.
"Both of them know what it was like; they both boarded, so they know how it works. William used to go to visit the late Queen and Duke of Edinburgh at Windsor while he was at Eton College, but that has to be organised. You can't just pop home when you want to.
"They are such a tight family unit; George will be missed. It will be like having an empty seat at the table."
Princess Charlotte, who turns 11 next month, and Prince Louis, who celebrates his eighth birthday on 23 April, will remain at home at Forest Lodge on the Windsor Estate for several years to come, and William and Kate will continue to be hands-on parents to all three of their children.
© Samir Hussein./WireImage'A happy family'
It is a close-knit home life that they have meticulously built by design, wanting to ensure that their family is as content and stable as possible, both now and in the future. For the couple, it is one of the secrets of their successful union.
"They're a great example of a happy family," says a friend of the couple. "William has always been intent on achieving that. Catherine also comes from a near-idyllic family background, what with her two amazing parents and close sibling relationships.
"The Prince and Princess of Wales have set a wonderful example themselves, not least in how they have brought up their children, affording them as much freedom in their growing-up years as they possibly can."
Milestone wedding anniversary
William and Kate will mark their milestone 15th wedding anniversary on 29 April with a low-key public outing, before celebrating with their children at home.
And they have much to celebrate. Over the years, they have surfed the ebbs and flows of public life and supported one another through some hugely challenging personal moments.
© Getty ImagesSince their earlier, newlywed days as the Duke and Duchess of Cambridge, embarking on major overseas tours and beginning married life together in a cosy cottage on the Isle of Anglesey, they have grown as a couple and taken on new challenges.
With her husband's unwavering support and guidance, Kate embraced royal duties, steadily growing in confidence and stature over the years, while also taking time out to nurture their young children.
William, meanwhile, has built on his decades of experience to become an influential world statesman. Together, they have cultivated significant and highly prized diplomatic soft power.
