Assuming that you're referring to the excerpt about a woman who was criticized because she's not quitting her job because she got a baby
She felt that the man is simple minded and simply not intelligent enough understand that she need the job to pay the bills, so rather than responding verbally, she chose to display her retort in other ways
hope this helps
It means conditions that are on the margin, the margin being that region of the operational envelope that is right on the edge between acceptable and unacceptable.
Could you please explain that