Meghan Markle to be Prince Harry's date at Pippa Middleston's marriage

It seems like things are getting serious between Prince Harry and Meghan Markle.

According to a source, Markle will be by Harry's side when they attend the evening party after the wedding ceremony of Pippa Middleton and financer James Mathhews, reports People Magazine.

The source also told People that protocol prohibits unmarried and un-engaged partners to attend the event.

Myka Meier, founder and director of Beaumont Etiquette shared that there is no formal "no ring, no bring" rule.

"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. 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," Meier said.

Recently, Harry flew out to Toronto 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.

Pippa Middleton and James Matthews' wedding is expected to be grand affair with Prince William and Kate's children Prince George and Princess Charlotte acting as a page boy and a bridesmaid, respectively.