By Liz McNeil
February 06, 2012 12:00 PM

Not so long ago, a typical night out for Drew Barrymore meant catching that next big indie band or meeting girlfriends at Chateau Marmont. Lately? Well, she’s been checking out art auctions at Christie’s and cooking dinner and watching Woody Allen classics at her Hollywood home with fiance Will Kopelman. Since Barrymore, 36, got serious with the preppy Park Avenue-raised art consultant, “she’s still Drew, but she has calmed down,” says a friend. “It’s almost like they’re already married.”

It’s a marked change for the former wild child, whose roller-coaster romantic history includes two divorces and a passel of famous boyfriends (see sidebar). In Kopelman, 34, she has finally found the stability she has long craved. “Her friends told her, ‘Do not let this one go,’ ” says another pal of the couple’s. “She’s the happiest she’s ever been.”

The pair, who got engaged in December at his parents’ Idaho vacation home, first met at a dinner party. “There were sparks right away,” says their friend. “They just knew.” Will’s father, Arie, former CEO of Chanel, and his stylish mom, Coco (who have been wed for 40 years), are part of New York’s society world, but they’ve fully embraced Drew. “We love her so much,” says Will’s sister author Jill Kargman. “She’s part of our family.” Will “would like to be a dad,” says their friend, but for now the focus is the wedding. “It will be very traditional, no elopement on the beach,” the friend says-and will happen before the end of the year. “It’s that When Harry Met Sally thing. Once you find the person you want to spend the rest of your life with, you want the rest of your life to start as soon as possible.”