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Jen & Vince: A Fine Romance

Thursday July 13, 2006 12:00 PM EDT

By October, work had led to play for the costars on the terrace of their Chicago hotel.

P-M / BAUER-GRIFFIN

Behind closed doors, that is. During a Mexican getaway last month, locals say the intensely private duo rarely ventured out, spending time at the Punta de Mita estate of Girls Gone Wild producer Joe Francis. Back at home, Aniston and Vaughn are equally determined to keep a low profile. "When they walk outside, they are so aware [of paparazzi] and know not to do anything. Not even hold hands," says the pal. "But when they are in private, they are very affectionate."

Which begs another question, sparked by the 9.5-carat yellow diamond Suzy Fabrikant ring a source says Vaughn bought Aniston while the pair were in Europe promoting The Break-Up. So what of rumors Vince popped the question? Reps for both starsvehemently deny they are engaged. "The engagement stories are fabricated," says her rep, who also denies Vaughn gave Aniston the ring. (Aniston herself has called such talk "silly.")

Still, there's no doubt the relationship has shifted into something more serious, evidenced in part by Aniston's willingness to troop along with Vaughn to view Chicago real estate and a recent openness on the part of the pair to discuss one another. Promoting The Break-Up in Paris, Vaughn said of Aniston, "She's the most sincere woman I know. She doesn't lie, she has a good heart." In the June issue of Harper's Bazaar, Aniston said that Vaughn was "a very deep human being, incredibly smart, loves history, is protective and very loyal to his family and friends." Plus, says a friend, "He's hilarious. He makes her laugh. That's a big part of the attraction."