No, the irony was not lost on Jennifer Aniston, making The Break-Up as she was going through her split with Brad Pitt. "When I got the phone call that a movie called The Break-Up was coming, I kind of laughed," says Aniston. A year later she's got the last laugh too. At the L.A. premiere on May 22, Aniston, 37, and costar Vince Vaughn, 36—who began dating while filming in Chicago last summer—kept their distance. But for a pair who have yet to publicly acknowledge their romance, the space was a strategic move—the one Pitt and Angelina Jolie used while promoting Mr. & Mrs. Smith —not a sign of trouble. "Vince and Jennifer are the real thing," says a pal of his. "They're both in a really great place." Though they remained apart at the afterparty at Westwood's Napa Valley Grille—Jen stuck close to her dad, John Aniston, 72—Vaughn put his hands on Aniston's shoulders before leaving and whispered in her ear. She left soon after, alone but smiling. As she said on the red carpet, "I'm just happy. There's no reason to be anything else, is there?"

HE SAID, SHE SAID ...

Promoting The Break-Up, Jen and Vince talked and talked about relationships ... just not about theirs, exactly

ON REAL-LIFE BREAKUPS:

ANISTON: There should always be a sense of closure and clarity so you can move cleanly into your next phase.

VAUGHN: All of us at moments go, 'Well, I think I could have handled that one better.' You learn from making mistakes.

ON HOUSEHOLD CHORES:

ANISTON: I'm a little crazy about doing dishes. I like a clean kitchen before bed.

VAUGHN: I don't like to do dishes. Not normally.

ON COMPROMISE:

ANISTON: Collaboration would be a better way [than compromise]. Collaboration is just talking—saying what you need.

VAUGHN: Men and women have to learn how to kind of give the other person their space.... I'm all of a sudden answering Dr. Phil questions!

INSIDE THE BREAK-UP

Do Jen and Vince have comedy chemistry? Take an exclusive peek at their big-screen split

So real life still seems to be working out pretty well for Vince Vaughn and Jennifer Aniston. But how will the couple play onscreen? Audiences will finally find out when The Break-Up, in which they play exes who each refuse to move out of the condo they share, hits theaters June 2. Vaughn and Aniston have a "Spencer Tracy-Katharine Hepburn kind of chemistry," says director Peyton Reed. Improvising to keep costars on their toes, Vaughn constantly "made Jen laugh." As for buzz about tweaks to the ending—do the characters get back together or not?—says Reed: "It's the ending I loved, and the only way this movie could end."