How Prince Harry, Meghan Markle, Prince William and Kate Middleton Interacted on Commonwealth Day

This marked their first public meeting since Harry and Meghan announced they were stepping down as senior members of the royal family.

The Fab Four, together once again!

All eyes were on Prince Harry and Meghan Markle on Monday as they reunited with Prince William and Kate Middleton to celebrate Commonwealth Day. The event marked Harry and Meghan's first public meeting with the Duke and Duchess of Cambridge since announcing their decision to step down as senior members of the royal family. Queen Elizabeth II, Prince Charles and Camilla, the Duchess of Cornwall, were also in attendance.

Once inside, Harry and Meghan took a seat next to Prince Edward and his wife, Sophie, just one row behind William and Kate. While there seemed to be some conversing between the Duke and Duchess of Cambridge, Edward and Sophie, it appears in videos that have since gone viral that Harry, William and their wives did not interact... despite an attempted hello from Meghan.

Royal expert Katie Nicholl was on hand for Monday's Commonwealth service, sitting just a few rows behind the Duke and Duchess of Sussex. She gave ET even more details on how the two interacted with the royal family throughout the day.

"One of the things that was so notable about today's service was the absence of any handshaking. This is of course because of the spread of the coronavirus," she said, referring to the worldwide spread of COVID-19. "I think the other thing I noticed as a spectator was there was no interaction between what we call the Fab Four. There was a brief hello, nod of acknowledgment between the four of them, but no moment for them to come together for a hug or even a conversation. So, it did feel like there was quite a lot of distance between the four of them."

"There wasn't really much of an embrace between them as we'd seen at last year's [Commonwealth Day]," she added. "It's hard to know whether that was because of strained relations or just because of the [virus] situation that we're in at the moment. But I can say, having watched both ceremonies, there was far less interaction. There seemed to be more distance between the two couples at this year's ceremony."

Nicholl told ET that both Meghan and Harry appeared to be in good spirits on Monday, with Harry seeming "very upbeat" and Meghan looking "happy" and "relaxed."

"I think it was inevitable that the Sussexes were really going to dominate the headlines this weekend, and indeed they have," she explained. "The big question on everyone's lips is what's next for the Sussexes, as they will step down from their royal duties on March 31. We understand that they're going to be putting a lot of effort into their philanthropic foundation ... but don't expect to see any big cash commercial deals anytime soon. I think that they are going to tread very carefully. They're going to want to seem to be really toeing the line, and certainly not upsetting the queen in any way, whatsoever."

"The Duchess of Sussex does divide opinion, but I think the general feeling over here in Britain is one of sadness, that we are losing Prince Harry and Meghan. This is an end of an era for Prince Harry, but it's also the start of a very new and hopefully exciting chapter for them as a couple," she continued. "My understanding is also that the couple does plan to come back, Harry particularly. His family is here, this is his home. His friends are here. This certainly isn't the last we will have seen them on British soil."

Despite what appeared to be an awkward encounter between the Fab Four, Nicholl believes that Harry will likely have a private chat with William and Kate in the coming days.

"I understand that [Harry] hasn't really had time to see his brother or his sister-in-law, so possibly this is an opportunity for them to spend some time together before Harry goes back to Canada," she said. "But my sources tell me that Meghan is keen, understandably, to get back to [son] Archie, who they left behind with Jessica Mulroney and their nanny in Canada."

Hear more in the video below.