"She will be aware that William is the royal and therefore they do get a member of the royal family there," veteran royals photographer Mark Stewart tells PEOPLE

By Simon Perry
Updated August 20, 2015 03:55 PM
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When it comes to royal wedding guests, there is perhaps no more coveted RSVP than one from Princess Kate.

So when Kate, 33, was absent from the wedding of Prince William‘s friends Bear Maclean and Daisy Dickson – he instead went with Kate’s sister Pippa Middleton – rumors flew about why she was a no-show.

Despite reports that she canceled at the last minute and that her name was still on the seating plan, PEOPLE has learned that she had previously sent her regrets about not attending and was never expected.

It is the latest in a series of “I do’s” that the royal mom has opted to skip. In 2011, she attended the wedding of William’s cousin Zara Phillips to rugby player Mike Tindall just four months after her own epic wedding, and her last such appearance was back in 2013 at the marriage of William’s polo-playing pal Mark Tomlinson.

Among the high-profile weddings she has skipped since then: The Memphis, Tennessee, wedding of William’s close friend Guy Pelly in May last year, which William, 33, and his brother Prince Harry, 30, attended with their longtime chums.

She also missed the June 2013 wedding of William’s former prep school pal Tom van Straubenzee, which was shortly before she was set to give birth to Prince George in July.

As a friend told PEOPLE at the time, she was “looking after herself. She just needs to make sure she’s okay.”

These days, she is likely still nursing her nearly 4-month-old daughter Princess Charlotte, as she was George back in September 2013 when she skipped the vows of another one of William’s closest crew, James Meade. (Both Meade and van Straubenzee were among those chosen by Will and Kate as Charlotte’s godparents.) “It would have been too difficult for her to be there all day and into the evening, when she’s feeding the baby,” a friend explained at the time.

But there is another reason why Kate opts not to be front-and-center at these society events alongside her husband: They are uncomfortable with the attention they bring.

Mark Stewart, a veteran royals photographer who covered some of the many weddings that Kate and William attended in the run-up to their own wedding in 2011, believes it is because they don t want to overshadow someone else’s big day.

“They do become the center of attention,” says Stewart, who covered many of the weddings Kate and William attended before their own. “Suddenly you can have 200 members of the public in a churchyard and that changes the dynamics.”

“They didn’t like the idea of upstaging the bride and groom – they wanted it to be about the couple getting married and not themselves,” Stewart adds. “And she will be aware that William is the royal and therefore they do get a member of the royal family there.”

Those who know Kate tell PEOPLE there is no doubt that she relishes the chance to be a “country wife” running a huge mansion 110 miles from London in Anmer while raising her two young children. With help from a beloved nanny and a housekeeper and Kate’s own hands-on mum, Carole Middleton, she can easily head out to events if she wants to.

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But, like millions of other couples, she and William are not alone in heading to family and friends’ special occasions separately. Kate previously attended the wedding of her cousin, Adam Middleton (who was also named as one of Princess Charlotte’s godparents) without her husband.

Now there’s another wedding on the horizon: William’s ex, Olivia Hunt, is set to wed 33-year-old barrister Nicholas Wilkinson. No doubt the bride-to-be will be watching her mailbox closely for the ultimate RSVP.

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