The next morning, he stands bare chested above her taking polaroids. He then moves astride her, continuing to take photos. She kisses his stomach and begins removing his jeans. He then lays on top and sex is implied to follow. No other explicit nudity.
There are 2 more times where sex is had in separate scenes while standing up but 1 is stopped quickly after started and after the woman had already started to moan but no nudity is shown. There are handfuls of references to to sex and affairs.
A couple are dancing on the sidewalk at night. The man begins kissing the married woman passionately. Later seen in his apartment, they are standing against a window and disrobing while kissing. They move over to his bed. We next see them both evidently naked, thrusting, having sex. Nudity includes his bare chest and her nipple.