The setting if "Nectar in a Sieve" is important to the understanding to the story. India's caste system helped define people's roles in life. One could not break out of their caste. Ruku's father's social position was not held in as high regard as it once had,so with no dowry to give her suitor, Ruku's father is forced to marry his last daughter to someone who is beneath her socially.
Ruku once had faith that her father's position would get her a husband who would be of her status, despite the low dowry and her looks. The social roles in India made it that women must have a dowry and be married or they would become a burden on their families. This society did not allow women to fend for themselves while still keeping their self-respect. These social norms forced women to marry men they did not know and therefore did not love. Ruku was lucky in the sense that although Nathan, the man chosen for her, was very poor, he was a kind and loving man.
This did not always prove to be true for other women. Ruku's own daughter was a victim of these roles. Ira did not conceive a child quick enough for her husband's liking and therefore he divorced her, sending her home a disgrace and burden on her family, Ruku and Nathan were loving and accepted her back with open arms,but again,it was not always like that. Social roles dictated what women's lives would become leaving women with little control over the destinies.