How has living in the city changed Nnaemeka's attitudes towards the old tribal ways?
It becomes clear that living in the city has helped to change Nnaemeka's attitudes from the tribal ways of his father. He is surrounded by more education in Lagos than in the tribal setting. This has enabled him to embrace a cosmopolitan approach to being in the world. The discrimination and prejudices that Okeke and the triabl ways offers towards someone like Nene have been put aside. Nnaemeka's living in the city has helped to foster this level of change.
At the same time, it becomes clear that life in Lagos is not as culturally bound by tradition as what Okeke experiences. Life in Lagos is more heterogeneous. The friends that Nene and Nnaemeka have come from varied backgrounds. While they might display initial reticence towards Nene, they are flexible and Achebe makes it a point that she "wins them over." It is for this reason that Nnaemeka does not really "get" his father's objections to Nene. When Nnaemeka argues that he wishes to marry for love, it becomes a statement of what living in the city has brought about in his consciousness. Nnaemeka understands marriage to be for love and this is a modern reflection, something that the environment of the city has helped to bring about within him. It is for this reason that one can see how living in the city has helped to establish a fundamental change within him and that accentuated when he sees his father and hears his objections being offered on such narrow and pedantic grounds.