How do Anju and Sudha keep their relationship strong?

In Sister Of My Heart, Anju and Sudha keep their relationship strong by devising creative methods to maintain an emotional connection.

In their childhood, both girls sleep in twin beds in Anju's room even though Sudha officially has her own room next to her mother. By the time they are old enough to attend school together, the girls come up with creative ways to stay close throughout the school day. Despite the fact that the nuns separate the girls for a time, the intervention of Anju's mother restores the status quo: Anju and Sudha, sisters of the heart, together always.

When disaster strikes and Anju's mother, Gouri Ma, has a heart attack, Anju is forced to agree to an early marriage. Additionally, Sudha is also obliged to marry due to her mother's fear that her attractive daughter would bring shame to the family name should she be sexually compromised. Nalini forces Sudha to agree to marry Ramesh despite Sudha's love for Ashok, a young man of a lower caste. Even in marriage, the two girls maintain their strong connection by marrying their husbands on the same day. They also go through the same ritualistic preparations for marriage prior to the double wedding.

Even after their respective marriages, both girls manage keep in touch through phone calls and letters. In Chapter 24, Anju takes a train to Bardhaman to visit Sudha in her marital home. Despite their love for each other, Anju is clearly worried about Sudha. The young, vivacious, and romantic girl she has grown up with has been relegated to the position of a household drudge by her imperious mother-in-law. Meanwhile, Sudha tries to put on a brave face so that she does not worry Anju. Here, you can see that, although both girls maintain contact, their emotional connection is slowly being eroded by their vastly different circumstances. Additionally, Anju must resolve her own jealous feelings about her husband's attraction to Sudha; this latent, emotional conflict threatens to drive a wedge between the two women as they navigate their adult lives.

When Anju and Sunil move to America, both women must rely on snatched conversations over the phone to maintain their relationship. Both women become pregnant at around the same time; however, Sudha's circumstances are vastly different from Anju's. Sudha's baby is a girl, and her mother-in-law wants her to abort the baby. Anju's baby is a boy who will be born in America.

As Sudha scrambles to decide her future, Anju is left helpless. She tells Sudha to go back home to their mothers, but Sudha tells her that her mother prefers her to go through with the abortion; the only other option is divorce if Sudha wants to save her baby. Both women know that divorce would be a life-long stigma for Sudha. Harassed beyond endurance with worry and fear, Anju secretly works at the college library to earn enough for Sudha's airfare to the United States. When Sunil discovers what Anju has been doing, he is furious, angry that Anju may be putting her baby and her health at risk.

Sunil also has his own reasons for not wanting Sudha to move in with them; he is still sexually attracted his wife's beautiful sister. Meanwhile, the last scene of the novel sees Anju and Sunil picking Sudha and her baby up at the airport. Despite having lived many miles apart, the women are together once more. As to whether they will continue to maintain their strong relationship in the future, the novelist is silent on that point.