Okonkwo sits in his hut and is hit with a wave of anger for having -for what he feels is - a bad son, that his God is punishing him for something that he has done. His son, Nwoye, had converted to Christianity, which was not the faith of his family or his culture, and had even gone to convert his mother and siblings. Okonkwo had seen this as a great betrayal since Nwoye was giving up on the culture and Gods of his father and also of his ancestors.
In the second part of the book, Okonkwa is exiled to Mbanta, which is a personal disaster for him, but it is also removed him for the village ata critical time for the village. While he is gone, the village that he once knew is not the same. When he returns, the village can no longer adapt to his somewhat deviant ways like it once had done. The changes that the British have brought on is one that Okonkwa has many stuggles with, with the rules, societal shifts and shifts in attitudes, and what it means to be a man in his Ibu culture. The changes that the British brought on brings on many changes, and it ends up pitting him against those he holds dear to himself.
Much of this is very tradgic because he has spent his life working to be respected, and he did this by using fear and anger as his driving force. He was considered to be a "strong man", working hard for this and achieving it at such as a young age, along with become rich and famous, while maintaining his strength and personality.only to be later exiled. It all started with the death of Ikemefume, who was a man that he viewed as a part of his family. SO, when Okonkwo was told by Okierika that being involved in the killing of Ikemefume would "not please the Earth, It is the kind of action for which the goddess wipes out whole families".