updated 06/11/2010 AT 7:00 PM ET
•originally published 06/14/2010 AT 8:45 AM ET
Anna Paquin and Stephen Moyer have shared some of True Blood’s steamiest sex scenes, but on the show’s set the couple keep their romance PG.
“They do keep their relationship to themselves. I mean, they’ll hold hands and they’re affectionate but it’s very tame,” says Carrie Preston, who plays waitress Arlene Fowler on the hit show, which premiered its third season Sunday night.
But the love between Paquin, 28, and Moyer, 40, who got engaged last summer, is obvious, says another cast member. “You can see that this is a wonderful real friendship,” Kristin Bauer, who plays the vampire Pam, tells PEOPLE. “There is just no way for them to have that not be evident.”