They're always the picture of elegance and happiness when they're spotted out and about together - whether they're visiting a school, attending an awards ceremony, or are out at a more relaxed sporting event.
But have you ever wondered why a public display of affection between the Duke and Duchess of Cambridge is such a rare sight?
The royal couple have been married for six years, and have been together for most of their adult lives. But the pair frequently refrain from holding hands in public, and when out on public events or royal engagements, have only occasionally been seen to come into close contact with each other - such as when they competed in a boat race, and William kindly comforted Catherine after her loss.
They also haven't been pictured holding hands many times throughout their marriage, the only occasions that spring to mind is their wedding day and at the birth of their daughter, Princess Charlotte.
But it turns out that the the answer behind why the adorable couple never publicly display their love for each other is actually far simpler than you might think.
An official royal etiquette expert confirmed that despite the fact there is no official ruling from the palace banning public displays of affection, the couple are simply just aware that it's probably more professional to refrain from doing so when they're out on official duty.
He went on to explain that "Technically, the couple are working representatives of the British monarchy. The couple are likely to show very little PDA, if any, to remain professional during their designated roles." Sounds fair to us!
Catherine and William also have a slightly different rule when it comes to another typical convention of married couples, too. It was revealed that Prince William never wears his wedding ring, despite the fact that the Duchess wears both her wedding band and engagement ring all the time.
But it turned out that the Prince simply doesn't like the feeling of wearing jewellery, and so chooses not to. So his lack of ring-wearing doesn't actually mean that his commitment to the Duchess isn't as strong as it's always been, thankfully.