Aniston with Joan Cusack,Friends With Money Director Nicole Holofcener and Catherine Keener Photo by: KEVORK DJANSEZIAN / AP
Jen Faces Her Future| Jennifer Aniston, Vince Vaughn
Much of credit goes to the 6'5" party boy who has become a fixture in Aniston's life. Vaughn is "a caretaker" by nature, says a close friend of the actor, who opens doors for Aniston – and fends off paparazzi with a firm "That's just not cool, dude." Work prevented Vaughn from accompanying her to Sundance, but he has been staying at her Hollywood Hills home, and the pair have become "inseparable," says the pal, sharing margaritas and listening to '80s tunes at clubs like L.A.'s Dragonfly.

By day, they hike together on the beach and, to the amusement of his buddies back in Chicago, take yoga classes. "She's changed Vince for the better," says the friend of Vaughn's trimmer look. The couple, he adds, are more than a rebound romance. "They met at a time when she needed someone to make her smile. He did a really good job of lifting her spirits, and now it's evolved into a true love affair."

Still, it was hardly love at first sight. Vaughn barely knew Aniston when they began filming The Break-Up together in Chicago in June, and Aniston, reeling from her very own breakup, "kept to herself," says an extra. Little wonder costar Jason Bateman says he "didn't notice any chemistry." Nor did casting director Jonathan Kinnas see opposites attracting. "She's so tiny, and he's giant, in size and personality," he says. "He's a partyer. She's on the quiet side. I wouldn't have put them together."

It wasn't until the wrap party in August, he adds, that "Vince and Jennifer were very chummy and we started to wonder." After filming ended, they grew closer. "I've never seen him care for anyone this deeply," says Vaughn's friend. And what does she see in him? "He's an alpha male. He's got fortitude and is resolute in life. But it really comes down to the simple fact that he makes her laugh."