What creates tension between Sagar and his wife in the novel, Mrs. Dutta Writes a Letter?

Unlike his wife, Shyamoli, Sagar is still interested in various aspects of his Indian heritage. He likes his mother's cooking and appreciates hearing humorous stories from his childhood, which makes it harder for him to deny her. He does try to train his mother in various American customs—such as how to use a washing machine—but he is unsuccessful. However, he does not confront his mother on many issues that Shyamoli has with her, which leads to tension between Sagar and his wife. When Mrs. Dutta's Indian behavior draws negative attention from a neighbor, Shyamoli and Sagar have an argument.