The Sopranos and Deadwood broke barriers of profane language and brutal violence; Sex and the City and Curb Your Enthusiasm bust the envelope of relationships and social comfort in comedy: The show chronicles three couples in various stages of crises in their sex lives.
As such, it achieves so much realism that many journalists wondered if the actors were actually engaging in some form of intercourse.
They are committed to those characters.
They are actors first. They do their work first. I think they do. Of course, common sense suggests that if they can fake Forrest Gump meeting dead presidents, flying superheroes and ancient Sparta, they can certainly fake a sex scene.
Her actresses, on the other hand, had to contain themselves. They wanted to assure everyone that they were professionals.