What is the "irony" in this novel

The Irony has to do with Okonkwo's rise and demise in his society. The fact that a once powerful and influential man could end up hanging himself is tragic. In a sense this is almost tragic irony. We can see Okonkwo's fall as he refuses to handle change. The coming of the white men causes a permanent change in the fabric of his culture. We know that Okonkwo will not be able to handle this.

The use of irony in things fall apart can also be curtailed

When nwonye okonkwo decided to abandon his root and culture to follow the white man culture

Nwonye wanted to follow Christianity and go to school to be literate rather than become a farmer as his father wished.. this is ironic because according to igbo culture the first son is supposed to continue or rather follow in step of his father in other to prolong the continuity of the the igbo culture

But at nwonye decision.. okonkwo is pained as his soon decided to abandon all he has been trying to uphold all his life