What does it mean if a man and a woman are having an affair and then they are rolling sheets?

This explanation is irresponsible. Ambiguous without actual commitment. At this stage, it is simply to help, or even to take advantage of it. What do you mean, all rolled up? Explain that the goal has been achieved, even people who like it will give up slowly, because it is too easy to get and don't want to cherish it.