Prince William and Kate Middleton 2
The Duke and Duchess of Cambridge are pictured during a walkabout in Ballymena town centre on Feb. 28, 2019 in Ballymena, Northern Ireland. Charles McQuillan/Getty Images

Prince William and Kate Middleton first tied the knot in 2011, however, before they were married, the Duke of Cambridge made his future wife a major promise that went against royal tradition.

Born to Michael and Carole Middleton, Kate is the oldest out of her siblings Pippa and James. According to the Amazon Prime documentary “Kate Middleton: Working Class to Windsor,” when Prince William proposed to his college sweetheart, he vowed she would be able to maintain a relationship with her family, despite her new royal status.

“Once you married into the Royal Family, you became a Windsor and that was that,” royal biographer Katie Nicholl revealed.

However, William was aware of how important Kate’s family was to her and promised she wouldn’t have to distance herself from her loved ones.

“When William asked Kate to marry him, he made it very clear that she wouldn’t have to leave her family behind her once she married into his family,” the commentator explained.

“He promised her that they’d always stay a part of the family and they have done. Whether it’s joining the Queen at Ascot or being on an important barge within the Queen’s fleet at the Diamond Jubilee celebrations, they’ve been there,” Nicholl added.

Prince William and Kate Middleton are now parents to Prince George, Princess Charlotte, and Prince Louis.