The theme of a piece of literature is the truth about human nature revealed in the story. A theme is often linked to a change in a main character. The theme of Chinua Achebe's short story "Marriage is a Private Affair" may be that the father, Okeke, realizes in the end that love, especially familial love, is more important than tradition. The conflict in the story revolves around Okeke's disapproval of his son's marriage to a girl who is outside of their ethnic group. Nnaemeka, from the Ibo tribe, marries Nene, an Ibibio woman, much to the dismay of Okeke, who objects to Nene for multiple reasons. Not only is she not Ibo, but she is also a teacher; and in Okeke's understanding of Christianity, women should not be teachers. Moreover, Okeke had intended for Nnaemeka to marry a girl from his small village because tradition usually dictated that fathers would arrange the marriages of their sons in the Ibo culture.
Because Nnaemeka goes ahead with the marriage anyway, Okeke basically disowns him and doesn't see him for eight years. In the meantime, the couple are happy and prosperous. They have two sons who soon learn about their grandfather and "insist" on being taken to him. When Nene writes to Okeke about her sons' wishes, he begins to soften and the suggestion at the end of the story is that Okeke will eventually see his son's family. While tradition is obviously important to Okeke, his family means even more, and in the last line of the story he worries that "he might die without making it up to them."