Question: how and why is ikemefuna killed?
Answer: He tells Okonkwo that the Oracle has decreed that Ikemefuna must be killed as part of the retribution for the woman killed three years before in Mbaino. ... Afraid to appear weak, Okonkwo kills Ikemefuna with his machete. When Nwoye learns that Ikemefuna is dead, something changes within him.