Prince William and Kate Middleton, the Duke and Duchess of Cambridge, are celebrating their 10th wedding anniversary on April 29, 2021, and one royal expert said that their union has been the best thing for William as Middleton became the source of stability for the royal who "desperately" wanted a stable life.

According to royal expert Victoria Arbiter, Prince William was craving stability because of his parents' failed marriage. Middleton was the "perfect antidote" for the Duke of Cambridge's difficult childhood. He was only 10 years old when his parents separated and he was a witness to his mother's struggles as William was Princess Diana's confidante.

Arbiter credits Middleton's "solid and secure upbringing" from her parents, Carole and Michael Middleton, which enabled her to be a "calming influence" on her husband. Because of this influence, the couple has built a life that's quite relatable and accessible to the public despite their royal status.

The royal expert also said that William and Middleton have "come into their own" after a decade of working alongside each other. They have embraced many things in their line of work, including adjusting to online royal engagements, thus making them effective at their jobs for the Crown.

Middleton was also praised for her efforts to help William and Prince Harry reconnect during the funeral of their grandfather, Prince Philip. She was seen starting a conversation with her brother-in-law and then stepped back when William and Harry talked to each other in public.

Royal expert Katie Nicholl said that Middleton has been trying very hard to patch things up with William and Harry as she was the first to be heartbroken when they had a falling out. Speaking with ET Online, Nicholl relayed that Middleton had big part in breaking the ice for William and Harry, as the whole world watched the royal family say their final goodbyes to their patriarch.

Meanwhile, BBC will air a special documentary for the 10th wedding anniversary of the Duke and Duchess of Cambridge. The special will air in the U.K. on April 30 and will feature guests like David Cameron, Dr Rowan Williams and Shane Connolly, John Ritter and Sir Clive Woodward, who were part of the royal wedding 10 years ago.

Prince William married the duchess after eight years of dating and two years of friendship. They have known each other since college since 2011. The royal couple now has three kids -- Prince George, Princess Charlotte and Prince Louis.