Prince William and Kate Middleton joined the traditional Christmas walk to St Mary Magdalene Church from Sandringham with their kids, Prince George and Princess Charlotte. But despite the smiles and happy faces, body language experts noticed some tension between the royal couple that might be a sign of a strained relationship.

Patti Wood and Traci Brown told Elite Daily that the Duke and Duchess of Cambridge showed a strong family unit, but their dynamic seemed a little less clear. There were said to be a few "unusual signs" that the two were not "totally in sync."

Wood explained that she usually saw Kate Middleton and Prince William very proper, showing an air of warmth and balance. But, everything was different on Christmas Day. It looked like the two were at odds with each other when they did the traditional Christmas walk.

However, opposite of what Wood saw, Brown insisted that they still had a glimpse of the excellent team that the public usually witnessed. Maybe, they were only dealing with some holiday stress at the time that was showing in their body movements. Whatever the reason was, the Cambridges vibe seemed to be quite ambiguous.

When the family was walking together, it could be seen that Prince William and Kate Middleton were leading their children. "Their chests are about even across, she with him. No one's pulling ahead, no one's pulling back," Wood said. This only showed that they wanted to show everyone a united front. However, the future queen consort's tight grip on her purse seemed to indicate an underlying tension.

Kate Middleton also displayed a bright smile that seemed to show she was happy to be out with her family. Although Princess Louis was left at home as he was too young to join the walk. Wood continued to say that she might be feeling a "great deal of pleasure" being seen as a family unit, although it was quite evident that she and Prince William might be dealing with some unknown stress that day.

Just like any other couple, Prince William and Kate Middleton are no different. They may also be dealing with relationship and family issues. Despite being royals themselves, their marriage is certainly not all coronations and grand.

Surely, according to Her, they deal with the reality of their relationship behind the closed doors of Kensington Palace. Hence, no one knows what is really going on in their marriage. The two may be hiding more secret behind-the-scenes that the public doesn't see. Prince William and Kate Middleton may be trying to hide their stresses and tensions, but it shows in their moves and reactions while doing their tedious royal duties.