The Cambridges will be celebrating Christmas Day with Queen Elizabeth II and the rest of the royal family at Sandringham. But before Kate Middleton and Prince William celebrate the holidays together, there was a point in their relationship that they had to be apart. In an unearthed report, it revealed how the Duke of Cambridge left the Duchess of Cambridge brokenhearted when they didn't spend the Boxing Day together.

When Prince William canceled their festive plans at the last minute in 2006, Kate Middleton was left devastated by the sudden change, per Express. In royal biographer Kate Nicholl's 2011 book, The Making of a Royal Romance, she revealed that the future queen consort was in tears, knowing that he couldn't see the second heir to the throne over the Christmas and New Year holiday.

At the time, before Prince William graduated from Sandhurst, Kate Middleton got an invite from Sandringham to join the royal family's traditional lunch. It was the first time that a girlfriend received an invitation from the palace, but she refused to be with her family for the Christmas break.

Also, she believed he would see her then-boyfriend on Boxing Day, but it didn't happen. Prince William promised to join the Middletons to celebrate Hogmanay at Jordanstone House. The place had a romantic setting, and Kate Middleton was waiting for his coming.

However, Prince William had a change of plan and decided to stay with the royal family instead, at the last minute. He told Kate Middleton about it, and she was devastated and left in tears.

Prince William saw no problem with it, but Kate Middleton believed it was a sign of "something more sinister to come." Confused about his feelings, William had a talk with his father, Prince Charles, and grandmother, Queen Elizabeth II, about his future with his then-girlfriend. The two advised him not to rush anything.

There were rumors the two were about to get engaged at the time. However, they decided to part ways in 2007, per Elle. Kate Middleton went on a vacation with her friends in Ireland. A couple of months later, they got reunited in June of the same year.

In 2010, Prince William finally popped the question while they were in Kenya, and Kate Middleton gladly said yes. In 2011, they got married in a fairytale ceremony at Westminster Abbey. The wedding of the year was witnessed by almost 72 million people across the globe. By then, they received the titles of Duke and Duchess of Cambridge.