Okonkwo has an excessive fear of being like his father, so as a result, he begins at an early age to prove to his tribe that he is strong and brave. As a result, he becomes an aggressive, angry, violent man in trying to distance himself from his father. His father was lazy and a poor provider for his family. Okonkwo's determination helps him succeed, but it also is partially responsible for his downfall. His anger and violence causes him to committ acts that damage his reputation. The more he achieves, the less he enjoys it because his fear of failure is always there, reminding him that he must continually prove himself to be better than his father. During his exile, Okonkwo learns the value of promoting unity within his community, but it's too late. When he returns to his village, the missionaries have already influenced his tribe, and it is Okonkwo's excessive pride that won't allow him to accept this. He's angry that his people don't support him in his fight against the Europeans, and he allows his fear of failure to blind him to the inevitability of European interference in the traditional beliefs of his people. Again, Okonkwo's anger and violence get the best of him, and he committs his final desperate act of vengeance. His suicide signals his spiritual alienation from his traditional beliefs.
Just as the title of this novel suggests, Okonkwo's downfall is caused by his inability to follow the mores of his culture and to adapt to colonization. His pride aids him breaking the mores of the clan. First of all, he beats his wife during Peace Week, which is unheard of. Next, he shoots a young boy when his gun explodes: "Violent deaths were frequent but nothing like this had ever occurred" (Chap.13). For this crime, he is banished for seven years. Next, as the Whites take over, Okonkwo kills the messenger: "Okonkwo's matchet descended twice and the man's head lay beside his uniformed body" (Chap.24). Lastly, Okonkwo commits the greatest sin of all, suicide.
As the culture of the clan falls apart so does Okonkwo's life as he fails to adjust to his role within the clan and later, his role as the clan's society is changed through the pacification by the White man.
Okonkwo is incapable of self acceptance. He bases his success and failure on his father's success or failure and in turn puts those same pressures on his children. He cannot cope with the evolution of the tribe and village when the missionaries arrived and his world begins to "fall apart." Like many elders in a traditional society, he feels he has no place in the "new" village and the old ways are as unnecessary as he is. Because he measures himself and others by standards that are no longer valid - he feels invalid and unnecessary.
Okonkwo is a traditional man who doesn't accept change very well. He also made a couple of other mistakes which led to his downfall for example: Beating his wife during the peace weak where violence is not condoned, he accidentally killed the son of the man whose funeral he was attending, which led to him being banished to his mother's lend for several years, and while he was away the church and colonists took over. When he came back to Umuofia things were no longer the same, yet he tried to fight back while others had already accepted their fate, leading to his arrest and finally the death of a messenger which was the last action he committed before his death.
I dont know
Okonkwo's inability to follow the law, forget his past with his father, his anger, and not accepting changes.