How Aniston found true love with Theroux, and all about the "small affair" she's planning

Here’s the thing about being Jennifer Aniston and being in love: The universe is invested. On Feb. 24 the star hit the red carpet in scarlet Valentino, her fianc , Justin Theroux, by her side.

Flashes shimmered, fans roared, and the pair ducked into Hollywood’s Dolby Theatre to take in the show. But there, the girl everyone presumes lives next door (who knew we all owned mansions?) was confronted by a friendly but curious employee who boldly asked That Question: Are you pregnant?

“No, I’m not!” replied Aniston, laughing politely. But, “I feel great,” she told PEOPLE later that evening. “Wonderful!”

And on the outside? Forget about it. “She looks the greatest she possibly could,” says Chris McMillan, her old pal and partner in her new hair-care line Living Proof. “Look at where she is in her life.”

There’s the man. There’s that ring. There’s a slate of films and new beauty ventures, renovating a $21 million L.A. estate in hopes of soon “normalizing and nesting,” as she recently told PEOPLE, and, yes, planning a wedding.

With her film, based on an Elmore Leonard novel, set to wrap in Connecticut on March 8, “Jen and Justin have a date” set for soon after, says a source close to the actress, noting that the twosome have designed their wedding bands and Aniston has a dress in mind. “It will be a small affair with their closest friends.” Likely among them: Aniston BFFs Courteney Cox, Chelsea Handler and Mandy Ingber, all of whom headed to New York to celebrate the actress’s 44th birthday at the Greenwich Hotel on Feb. 11.

The bride-to-be “is crazy about Justin and can’t wait to be his wife,” says the source. “She plans on privately changing her name to Theroux. She likes the way it sounds and jokes that [Jennifer Theroux] sounds very posh.”