Daniel Radcliffe Seen Kissing Costar Erin Darke in Sundance
01/19/2013 AT 01:00 PM EST
At the Grey Goose Vodka Lounge dinner at the Blue Door in Sundance for the movie Kill Your Darlings – about a 1944 murder involving the literary heroes of the Beat Generation, with the actor playing poet Allen Ginsberg – Radcliffe, 23, was having some fun by dancing with costar Michael C. Hall, who attended with his novelist girlfriend, Morgan Macgregor.
But it's Darke who seems to have a leg up with Radcliffe.
While Macgregor sat on the sofa flanked by Hall (his arm around her) and Radcliffe, Darke sat in the chair next to the couch and continuously rubbed Radcliffe's knee. They also shared a brief kiss.
Outside together later, the two huddled – with Darke's arm around Radcliffe.
One partygoer who worked on Kill Your Darlings told PEOPLE that Darke was Radcliffe's "girlfriend," but in a brief interview with PEOPLE, Radcliffe dodged the question and spoke instead about how he enjoyed being in Sundance with the entire cast.
"Erin? Oh, Erin Darke?" he said. "Yeah, the whole cast is here. It's fantastic."
Another partygoer told PEOPLE, "They've been dating for a while but have been debating going public."
– Patrick Gomez