OK I just worked out what SO means! *duh* Actually I think if it were me I would prefer to have the SO there. I would feel MORE guilty and unfaithful if they weren't. That way the SO can see that it's all just business as usual and see how clinical it all is - what with the camera and sound boom in your face and a dozen smelly crew members standing by. Otherwise you could have a conversation like "Honey, how did filming go today?" "Oh you know.." "No I DON'T know -TELL ME, Mr Sex Scene Actor-Boy!!" LOLOL! I guess if that's the way an actor prefers it then I'm sure a director will go with whatever makes it easier for the actor to get the best performance so to speak.