06/14/2013 at 02:00 PM EDT
Leaving their little one
for the night, Ali Larter
and hubby Hayes MacArthur stepped out for date night on the rooftop of Hotel Americano in New York City last week.
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