Bradley Cooper on Renee Zellweger: “I Just Love Her”

 GERALDINA AMAYA/FRANK ROSS MEDIA

What a difference four years makes!

When Bradley Cooper and Renee Zellweger began filming thriller Case 39 way back in 2006, they were perfect strangers.

Now dating for over a year, the ultra-private, real-life couple opened up about getting acquainted on the horror film, in which they play a flirty but platonic social worker (Zellweger) and psychologist (Bradley).

"Can't say enough about her," Cooper, 35, raved to Entertainment Tonight. "I never met her before this movie, but I just love her. I love coming to work. I love acting with her. I can learn so much from her."

Zellweger, 41, added of her love: "He's a great actor! I just got so excited, not believing that I was going to go work with him." (Lately, Zellweger has been palling around in L.A. with Gloria Cooper, the A-Team actor's mom.)

Cooper gushed: "It's just so easy to work with her!"

PHOTOS: Rar! See a super-buff Bradley shirtless!

The couple have been notoriously tight-lipped about their romance. In the June/July issue of Details, Cooper refused to chat about Zellweger. "I just can't," he said.

"They're so down to earth and [they] spend time with family whenever possible," a source close to the couple told Us  earlier this year. "They're the real deal!" added another pal.

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