Cressida Bonas is being welcomed into the royal fold.
Prince Harry's girlfriend spent last weekend with him at Sandringham - the Queen's estate in Norfolk, east England - and although Queen Elizabeth was away at the time, her invite is a significant symbol of acceptance by the British royal family.
A source told The Sun newspaper: "A weekend at Sandringham is almost a rite of passage for any future royal bride.
"Harry has an extremely demanding role in the military and it's the perfect place for him to unwind with those he dearly wants to be around.
"Cressida has been given the Royal seal of approval. Of that there is no doubt. Harry is smitten and treats her like a princess."
Cressida's inclusion at the Christening of Prince George last week is another sign 29-year-old Harry - who was introduced to the socialite in May 2012 by - could be ready to move their relationship to the next level.
However, inviting Cressida was a move which had to be handled with care, as Prince William and Duchess Catherine had to be sure she wouldn't distract from their son's Christening.
The source added: "William and Catherine have grown very fond of Cressida and the time was right to move things forward in terms of protocol.
"The christening was tricky. No one wanted a situation where Cressie's presence may have diverted attention away from Prince George.
"But considering Harry's age and this very significant step, the feeling is this relationship is very special indeed.
"The Royal family are more guarded than ever. But the public will soon start seeing Cressie with Harry more and more often, albeit within a controlled environment."
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