Meghan Markle Will Attend Pippa Middleton's Wedding as Prince Harry's Date - but There's a Catch

Meghan Markle is set to attend Pippa Middletons wedding to financier James Matthews as Prince Harrys date, PEOPLE has learned.

A source tells PEOPLE that while Markle, 35, will not be on hand for the ceremony at St. Mark’s church in Engelfield, England, on May 20, she will be by Harry’s side when they attend the evening party after the nuptials. The source adds that protocol prohibits unmarried and un-engaged partners to attend the event, but they are more likely to attend the big bash afterwards, which tends to be less formal.

The fact that she will attend the wedding - even if it’s the post-church nighttime bash - is yet another sign that the Suits actress and the prince, 32, are getting more and more serious.

Over the weekend, Harry flew out to Toronto (where Markle films Suits) to spend Easter weekend with his girlfriend - skipping the usual royal Easter tradition of attending services at St. George’s chapel at Windsor castle with Queen Elizabeth II. (Princess Kate, Prince William and other senior royals were on hand for the services this Sunday - with Kate showing off her perfect curtsey to the Queen.)

Myka Meier, founder and director of Beaumont Etiquette, tells PEOPLE that while there is no formal “no ring, no bring” rule, it isn’t surprising that Markle didn’t get an invite to the church wedding as Middleton would likely want to keep her actual wedding small.

“I would not be surprised if Prince Harry was not given a plus one, as the wedding guest list would have most likely been made in fall of last year when Prince Harry’s relationship with Meghan was not as public,” Meier said. “I typically recommend if someone is married, engaged, considers themselves to have a serious significant other, or is traveling in for the wedding, they should receive a plus one. Pending how intimate Pippa wants to keep her wedding, she may very well follow the no ring, no bring’ rule.”

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Middleton’s wedding is expected to be a royal affair, with Will and Kate’s children Prince George and Princess Charlotte acting as a page boy and a bridesmaid, respectively. Naturally, William, Kate and Harry will also be in attendance.

Hopefully Markle’s trip across the pond is a sign that there will be another royal wedding in the not-so-distant future.

This article was originally published on PEOPLE.com