In Things Fall Apart, Okonkwo kills himself because he realizes that the Umuofia he devoted his life to defending has changed beyond repair, and because his own rigid idea of strength leaves him unable to live in that changed world. After he kills a court messenger in an attempt to push the clan into war against the British colonizers, he sees that the other men will not follow him. Instead of rising up, they ask, “Why did he do it?” Their attitude shows him that the old values of Umuofia no longer unite the clan.
Okonkwo has spent his whole life trying to be the opposite of his father, Unoka, whom he saw as weak and feminine. He builds his identity around aggression and masculine honor. Earlier in the novel, this fear drives him to kill Ikemefuna even after Ezeudu warns him not to participate because “the boy calls you father.” Okonkwo acts violently again and again because he believes any sign of hesitation will make him appear weak. By the end of the novel, however, the clan no longer respects violence in the same way, and many people have accepted the new religion and colonial government.
Okonkwo understands that the White men “ha[ve] put a knife on the things that held us together and we have fallen apart.” The community is divided, and the traditions that once gave his life meaning can no longer hold the clan together. Since Okonkwo cannot imagine adapting, compromising, or living under colonial rule, suicide becomes his final act of control and resistance.
His death is also tragic because it violates the very traditions he tried to defend. In Umuofia, suicide is an abomination, so his clansmen cannot even touch his body. The man who devoted himself completely to tradition dies cut off from it. Achebe turns Okonkwo’s final act into a contradiction: his obsession with strength and honor ultimately leaves him isolated from both his people and his culture.