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Justin Theroux introduced girlfriend Jennifer Aniston to his documentarian cousin, Louis Theroux, in London on Wednesday night, an observer tells Us Weekly. After Aniston, 42, hit the red carpet premiere of Horrible Bosses, she and Theroux, 39, headed (hand-in-hand) to Shoreditch House, a swanky members-only club in London. According to the witness, Justin's cousin Louis joined the pair half an hour after their arrival.

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"Louis obviously approved [of Jennifer]," the insider says. "It looked like they were having a great time, and they all seemed instantly at ease with each other. Justin looked proud of Jen and seemed quite manly and protective."

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The trio enjoyed dinner and drinks together, and another observer told Us Aniston "was really chilled out and seemed blissfully happy."

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When asked about her personal life on a Good Morning America appearance last month, the Friends star gushed: "Yes, I'm very happy... I'm extremely lucky, and I'm extremely happy."

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