The actress plans to wed David Thomson, the 10th richest man in the world

Kelly Rowan, who played resident party planner and family matriarch Kirsten “Kiki” Cohen on The O.C., is engaged to Canadian billionaire David Thomson, Rowan’s rep confirms exclusively to PEOPLE.

The couple, who plan to marry before the end of the year, have been dating since last year after meeting in Toronto while she was working.

“Their family and friends couldn’t be happier for them,” says a source close to the couple, adding, “She’s really happy.”

The Ottawa-born Rowan, 41, played Adam Brody’s mom and Peter Gallagher’s wife on the FOX series. She also served as executive producer of In God’s Country, a movie for Lifetime in which she starred.

She is also producing Blithe in Virginia, a movie with her former O.C. costar, Melinda Clarke.

Toronto-based media mogul Thomson, 50, is Canada’s richest man and the 10th richest man in the world, according to this year’s ranking of billionaires by Forbes magazine, which also says he is the divorced father of three.