'It Was Awkward': Prince Harry & Prince William Found Windsor Outing With Wives 'Hard,' Spills Source

The ice-cold feud between Prince Harry and Prince William's wives couldn't even be warmed by their love for Queen Elizabeth II.

A source spilled there was "awkward" tension between the in-laws following the Prince of Wales' invitation for the Duke of Sussex and his wife, Meghan Markle, to join him and Kate Middleton for a honorable stroll outside of Windsor Castle on Saturday, September 10.

"It was awkward. Both couples found it hard," an insider dished to a news publication. "They were in a stoic spirit of just getting through it for the Queen."

The public outing was rare for the royal pairs, as it was the first sighting of the estranged brothers together since the death of their grandmother on Thursday, September 8.

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As OK! previously reported, the newly named Heir to the throne found the walk to be "an important show of unity at an incredibly difficult time," as the entire nation and world began to mourn the passing of the longest reigning British monarch.

"It's such an extraordinary historical moment and also a deeply personal one for the family that you'd hope and think that all members of the family would unite and support [the King] especially," stated an additional source of King Charles III. "And perhaps some of those wounds can be healed in the process."

Although the royal couples all share the same overarching love for Queen Elizabeth, it seems nothing is able to stop bitter tensions between the sister-in-laws.

OK! recently reported that Kate appeared to "freeze out" Meghan with cold-hearted glares during the weekend leading up to Her Majesty's Monday, September 19, funeral. And while they seemed to be a united front, body language experts pointed out Meghan was clearly uncomfortable while surrounded by royal members.

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“Quite unlike the confident Meghan we know, Meghan appeared ill at ease during this encounter, which is not surprising given the recent criticism that she has faced,” explained body language expert Katia Loisal in regard to the intense interactions between Kate and the Duchess of Sussex.

"Meghan, with her head tilted down, covering her face, indicating feelings of shame and victimization," noticed another body language expert, Dr. Robi Ludwig, during the Queen's funeral services. "There is a sense that she is upset and uncomfortable. Her body language indicates a disconnection with the other family members and a discomfort with her current status among the working royals."

"She is definitely feeling the coldness and is very uncomfortable about it," the expert continued. "She is like a fish out of water, and it's obvious."

People reported the couples finding the encounter outside of Windsor Castle "awkward" and "hard."