Kate Middleton's not the only commoner hanging out with royals these days.

On Wednesday, Jennifer Aniston broke bread with Prince Robert of Luxembourg during a super-luxe, seven-course meal prepped by acclaimed chef Thomas Keller at the Vibiana Hotel in Los Angeles.

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Alas, it wasn't a fairy tale love match for Aniston, 41: For 16 years, His Royal Highness Prince Robert, 42, has been happily married to Princess Julie, with whom he has three kids.

The Prince is also chairman of Domain Clarence Dillon wines, which threw the gourmet bash (also attended by Sacha Baron Cohen, Quincy Jones, Adrien Brody and other celebs) to fete the 75th Anniversary of the Chateau Haut-Brion.

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Regardless, single lady Aniston is certainly in a festive mood lately. On Dec. 4, she welcomed Courteney Cox and 100 other pals into her Beverly Hills manse for an elaborate holiday party, complete with a roaring fire and yuletide tunes.

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"She stayed in all day preparing," an insider tells Us. "The house was decorated with candles and white lights ... Everyone had a great time!"

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