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Either they're REALLY comfortable with one another or there's trouble in paradise! These days we just can't tell...

Jennifer Aniston celebrated her 45th birthday at Soho House in West Hollywood on Tuesday evening, and though she had a blast with her friends like Jen Meyer and BFF Courteney Cox, fiance Justin Theroux was 3,000 miles away in New York City partying it up with newly-single Orlando Bloom.

Still, Jen didn't seem to mind. A source tells Us Weekly it was a "mellow fun dinner" and the birthday girl "was happy" to be there. And in his defense, Theroux is working on the new HBO show Leftovers in the Big Apple, and he's been spending time with the family of the late Philip Seymour Hoffman following the actor's shocking death earlier this month.

One clue that the two aren't split up? When Jen interviewed Gloria Steinem at the Makers Conference in Ranchos Palos Verdes earlier this week, she wore a "T" necklace, which we're going to go ahead and guess stands for Theroux. But when's the wedding?!