Like Water for Chocolate

Tita, as per the De La Garza family tradition, is forbidden to marry. Her duty is to care for her mother until the day her mother dies. Therefore, when Pedro, the boy from a neighboring ranch that Tita has fallen in love with, comes to ask for her hand in marriage, Tita's mother Mama Elena, refuses; she instead offers her other daughter Rosaura to Pedro as his wife. Pedro accepts as the only way for him to be close to the woman he loves is to marry her sister. Tita, with the help of the old "Indian" (Native Mexican) ranch cook Nacha, bakes the wedding cake while weeping her sorrow and shedding her tears into the cake batter. The resulting cake causes a severe, crushing longing for their one true love in all those who eat it, causing vomiting, crying, and sorrow in not only the wedding guests but also in Nacha, who dies from the heartache of missing her one true love; Tita become the head ranch cook afterwards.
A year later, Tita's emotions again infuse a meal that she cooks. While using the roses that Pedro has brought her to celebrate her first anniversary as the ranch cook, her burning passion for Pedro transfers to her sister Gertrudis, who, overcome with lust, attempts to cool down by taking a shower, only to be scooped up and carried off by a passing soldier.
Rosaura gives birth to a baby boy, but Tita miraculously is able to nurse the child after the death of his wet nurse, and she bonds with him. However, Mama Elena is suspicious of Tita's intentions toward Pedro, and sends Rosaura and Pedro away. Tita blames the consequent death of the baby on Mama Elena and, grief-stricken, Tita falls into a catatonic-like state.
Dr. John Brown, a kind and gentle widower with a young son, takes Tita away to care for her in Arkansas. Dr. Brown often talks about his life philosophies to Tita, explaining that he thinks there is a flame in everyone, and if it goes out or gets too bright, they die. Tita eventually enters into a relationship with Dr. Brown after recovering, and reluctantly plans to marry him.
During a raid by rebels, Mama Elena is killed by soldiers. Rosaura and Pedro return for the funeral and move back into the family home which Mama Elena left to Rosaura.
Rosaura soon gives birth to a second child, a girl named Esperanza for whom Tita takes over the feeding duties. Rosaura plans to continue the tradition of forbidding her daughter to marry, angering both Tita and Pedro. Soon after, Dr. Brown is called away on business and Pedro and Tita give into their shared passion and make love. Mama Elena returns to haunt Tita, convincing her that she is pregnant with Pedro's child. That night, Gertrudis returns to the ranch with her husband, the soldier who carried her off. She helps Tita banish Mama Elena and realize that her pregnancy was imaginary. Upon Dr. Brown's return, Tita tells him that she slept with another man and he reluctantly allows her to break their engagement.
Years pass, and Rosaura dies of "severe digestive problems". Her daughter Esperanza, freed from the curse of being forced to care for her mother for the rest of her life, marries Dr. Brown's son. At the wedding of the two young people, Pedro confesses to Tita that he still loves her, and wants to marry her. Tita and Pedro then make love, but Pedro dies just as he has a sensuous orgasm. Recalling Dr. Brown's words, Tita then swallows matches to regain the flame inside her, and sets the entire house on fire in the process. The daughter of Esperanza, named Tita after her great-aunt, returns to the house and discovers Tita's cookbook, which contained her recipes and told of her and Pedroâs love story.

Question: Who is forbidden to marry?
Answer: Tita