Ashton Kutcher and Mila Kunis
Jon Kopaloff/FilmMagic; Kristina Bumphrey/Startraks
and Mila Kunis
are apparently getting more comfortable going public with their new romance.
According to an onlooker, the pair "showed up as a couple and left as a couple," on Thursday night at the Jobs
movie wrap party at new L.A. restaurant Duplex.
At the 300-person fete, which included guests Diddy
and Dermot Mulroney, the lovebirds, "appeared to be lighthearted and in good spirits, and hardly left each other's side," the source tells PEOPLE. "They stayed within five feet of each other practically the entire evening. It looked like young love."
Linked since April
, the former That '70s Show
costars, "were totally comfortable," the insider says. "They were very friendly and spent a lot of the night engaging others in conversation while maintaining close and casual affection."
During the party, that had guests feasting on hors d'oeuvres by Executive Chef Lauren Cartmel, Kunis sipped on Grey Goose and soda water, while her man had Grey Goose and tonic water, along with Pinot Noir. The duo stayed for a couple of hours. – Jennifer Garcia