Ikemefuna was sent to Okonkwo's household to await his time to be sacrificed for the compensating of the woman that was murdered by the Mbanta tribe. Ikemefuna became a type of double sacrifice. He lost his family or they lost him. Also, Okonkwo had grown fond of Ikemefuna. The boy called Okonkwo father.
When Ikemefuna was sacrificed, Okonkwo was instructed by a clan member to not take part in the sacrificing:
That boy calls you father. Do not bear a hand in his death.
Okonkwo did not want to appear weak. Out of fear of appearing weak, he took part in killing Ikemefuna. Then Okonkwo could not sleep for days. Fear caused Okonkwo to react violently.
Ikemefuna's sacrificial death was a type of foreshadowing of Okonkwo's own death. Okonkwo killed Ikemefuna out of fear of being thought of as weak. Likewise, Okonkwo hangs himself out of fear. Because his clan would not fight the white Christians who were taking control, Okonkwo could not live with the changes, thus he hung himself. Out of fear, Okonkwo reacts violently. He killed Ikemefuna out of fear. He killed himself out of fear. He died without honors, just as his father Unoka.