What sociocultural limits restrict the freedom of Asunción?

In Carlos Fuentes's novel, Jaime Ceballos is the protagonist, Rodolfo is his father, Asunción is his father's sister, and Jorge Balcárcel is her husband. The action takes place in the 1920s, just after the Mexican Revolution. The Ceballos family, proud to trace their descent back to Spain, had been wealthy elites. One of the revolution's achievements, however, was agrarian reform, which included the expropriation and redistribution of huge estates, or haciendas.
Both families lost land and related income. Asunción found security of a sort in her marriage to Jorge, but her control over family affairs is severely proscribed by the strongly patriarchal system. Rodolfo, in contrast, married a woman of lower status, and his sister manages to unseat her and take over their family's home. Her hopes of continued power and financial survival are now invested in her nephew, who, as a male, will receive inheritance. She also has no children of her own, so she cannot help her husband continue his family's male line.