UK’s Prince Harry and his fiancée, American actress Meghan Markle, were spotted sharing an inside joke that left many on social media scratching their heads.

The couple attended the Commonwealth Day service at Westminster Abbey on Monday where singer Liam Payne performed his version of John Mayer’s “Waiting on the World to Change.”

However, when the One Direction heartthrob finished his rendition, Harry, 33, was spotted glancing at Markle while making a face and raising his eyebrows. The royal’s expression caused his bride-to-be to giggle and bury her face into her chest.

The moment was caught by a viewer on Twitter.

The event marked the 36-year-old “Suits” star’s first official public appearance alongside Queen Elizabeth II.

Many on social media wondered what could have caused the commotion between the pair.

“Meghan sometimes seems immature,” tweeted one user. “Be it nerves or whatever, she should follow the Queen’s lead, not Harry’s Princely shenanigans, when at ALL formal occasions; particularly with so many detractors picking apart her every move.”

“I’m glad she is living life to the fullest, as do I,” chimed another. “However, she chose a new life that comes w/RESTRAINTS. Queen Elizabeth II ACCEPTED her into& she agreed to ABIDE by as a NEW, FOREIGNER, coming into an ‘ancient’ institution,” chimed another. “She has MANY detractors-I wish her well.”

Still, some were quick to defend the royal-to-be.

“With all that [Meghan] has to go through before this wedding if she can still smile that is really wondered,” wrote one user.

“Oh c’mon! Lighten up!” added another. “Let the woman live and be happy.”

Payne, 24, didn’t seem worried about the response he received from the royal family for his singing.

“Such an honour to be asked to perform at the #CommonwealthDay service in front of the @royalfamily!” he tweeted. “Hope you enjoyed my cover of @JohnMayer’s Waiting For The World To Change.”

Payne then shared a photo of himself shaking Queen Elizabeth’s hand, tweeting, “Today was an absolute pleasure to be a part of #CommonwealthDay.”

Kensington Palace announced in November 2017 the couple got engaged after meeting in the summer of 2016 through a mutual friend.

The upcoming wedding will be the first grand royal wedding since Harry’s brother Prince William married Kate Middleton in 2011.

The highly anticipated nuptials will take place Saturday, May 19 at St. George’s Chapel. The ceremony will officially kick off at 7 a.m. ET / 4 a.m. PT, and be followed by a carriage procession.

After their ride Harry and his bride will attend a reception for the congregation guests at St. George’s Hall, followed by a private evening reception held by Prince Charles for their close friends and family.

In February, Markle was appointed a secretary to help handle her increasingly busy royal schedule and duties.