Ali Larter & Hayes MacArthur's Lovey-Dovey Champagne-Filled Date Night
06/14/2013 AT 10:00 AM EDT
Celebrating Perrier-Jouet's Enchanting Tree launch, the pair sipped on champagne and seemed "so in love," according to an onlooker.
"Ali kept touching Hayes's knee," the source says. "She would stop to talk to people and then would always come back to him."
MacArthur may have been the most important person at the fête for Larter, but to the rest of party, the actress was the belle of the ball.
"She had everyone's heads turning in a stunning, gold champagne Hervé Léger dress," the source continued. "Throughout the night, Ali was approached by fans to take photos and she happily obliged."
– Dahvi Shira