Three years after splitting from David Arquette, Courteney Cox is dating her Cougar Town costar Brian Van Holt Credit: Larry Busacca/Getty Images

Courteney Cox has turned her onscreen ex into an offscreen love. The actress, 49, is officially dating her Cougar Town costar Brian Van Holt, who plays her ex-husband on the TBS series, the new issue of Us Weekly reveals.

"They've been going out for about six months," one insider tells Us of the couple, who have been linked off and on since Cox split from actor David Arquette in 2010. (Arquette once told Howard Stern that his ex and Van Holt were having "an emotional affair.")

The source adds that Cox is more comfortable taking her relationship with Van Holt out in the open now that Arquette has moved on with girlfriend Christina McLarty. Proof? On July 10, the costars "acted like boyfriend and girlfriend" during dinner at West Hollywood's Chi Lin, a witness tells Us.

Van Holt is also tight with Cox's pals and, more importantly, with her daughter. "The girl was extremely comfortable with Brian," an onlooker says of Coco, 9, who visited the Cougar Town set last fall. "She treated him like a dad or an uncle."