In the story, Mariam is indeed a figure of sacrifice. Here is one quote that demonstrates this:
She could feel his hand working at his belt, at the drawstring of her trousers. Her own hands clenched the sheets in fistfuls. He rolled on top of her, wriggled and shifted, and she let out a whimper. Mariam closed her eyes, gritted her teeth. The pain was sudden and astonishing. Her eyes sprang open. She sucked air through her teeth and bit on the knuckle of her thumb.
Here, Mariam's meek submission to Rasheed leads to physical injury. Essentially, Mariam sacrifices her feelings for Rasheed's selfish pleasure. She does this not because of a misguided desire to please her husband but because society demands her obedience to her husband. For a woman such as Mariam, there is no recourse to justice.
For her, all these months later, their coupling was still an exercise in tolerating pain. His appetite, on the other hand, was fierce, sometimes bordering on the violent.
The above quote demonstrates that pain is a constant companion for Mariam in the beginning of her marriage. She sacrifices her physical welfare for Rasheed because of her fear, sense of responsibility, and low self-esteem. Mariam believes that her plain looks consign her to a life of servitude to an abusive husband. Even after she finds Rasheed's pornographic magazines, Mariam tries to rationalize her husband's brutal treatment:
He was a man. All those years without a woman. Could she fault him for being the way God had created him?
A few more quotes that show how Mariam sacrifices herself are:
I won't have the two of you living on the run, like fugitives. What will happen to your children if you're caught? . . .
Who will take care of them then? The Taliban? Think like a mother, Laila jo. Think like a mother. I am. . . .
For me, it ends here. There's nothing more I want. Everything I'd ever wished for as a little girl you've already given me. You and your children have made me so very happy. It's all right, Laila jo.
Here, Mariam sacrifices herself so that Laila and her children can escape to safety. Mariam understands that two women on the run will alert the Taliban. So, she chooses to stay behind to take the blame for Rasheed's death. Mariam spends ten days in prison before she is executed. Her last thoughts are of Laila, the children, and God.