updated 12/20/2004 AT 01:00 AM EST
•originally published 12/20/2004 AT 01:00 AM EST
Lopez—who also taped an appearance on Star Academy, a French version of American Idol, in which she sang with contestants—"was obviously very excited about him being there," says an onlooker. "There was a lot of good-natured give and take. At one point she told us, 'If you get excited, here is the dance floor.' And Marc said, 'Yeah, I'll dance.' " Not even the behavior of a few guests at the Stockholm party, who talked through some of her songs, appeared to spoil Lopez's mood. "They both seemed really relaxed and enjoyed their time together," says a guest at that event. As they left, "they were holding hands and kissing each other in the backseat of the car."