Bradley Cooper and Renee Zellweger have reached their limit.

After less than two years together, the couple have split, multiple sources confirm to Reps for both Cooper and Zellweger had no comment.

Limitless star Cooper, 36, first met Oscar winner Zellweger, 41, six years ago on the set of their thriller Case 39 -- but romance didn't bloom until summer 2009.

In the interim, both stars had short-lived marriages: Cooper to actress Jennifer Esposito, Zellweger to singer Kenny Chesney. Both unions petered out in less than six months. (Find out how Bradley explained his short marriage to Esposito.)

After being photographed dining together in NYC in July 2009, the duo were spotted kissing in Spain in early August; the next week, he took her to his Philadelphia home town.

The couple remained steadfastly tight-lipped about their relationship in the press. Asked about Zellweger by Details magazine in the June/July 2010 issue, Cooper retorted, "I just can't."

"They're so down to earth and [they] spend time with family whenever possible," a source close to the couple told Us last year. Indeed, Zellweger was spotted frequently in the L.A. area palling around with Cooper's mother.

"They're the real deal!" another insider said of the twosome at the time.

During press for his new movie Limitless, Cooper stayed typically mum on his love. On the Howard Stern Show on Monday, Howard Stern grilled the Hangover star about Zellweger; Cooper simply denied any engagement plans.