Why does Nene think Nnaemeka should write to his father?

Nene thinks Nnaemeka should
write a letter to his father, Okeke, to give him the good news about Nene and Nnaemeka's
engagement. They love each other very much and are happy and excited to be
planning their wedding. But Nnaemeka is thinking about waiting for six weeks instead of writing
a letter right then, so he can tell his dad in person about the engagement. Nene disagrees and
says: "He should be let into our happiness now." She means that the news of the
engagement is exciting and happy, and Okeke should know as soon as possible so he can share in
their joy.

All this is very normal if you're in the mindset of a typical
modern reader; we marry for love, we choose our own life partners, and these days we usually
don't completely freak out if someone falls in love with a person from a different religion or
race.

But Okeke and his son belong to the Ibo tribe in Nigeria, and their
culture is extremely different. What Nnaemeka hasn't really explained very well to his
soon-to-be wife is that Okeke is likely to hate the idea of his son
marrying Nene. She's the "right" religion, but she isn't from the Ibo tribe, and she
hasn't been chosen for Nnaemeka in an arranged marriage. For those reasons, Okeke finds the
marriage not just a bad idea but a source of deep shame for his family. As you can see, Nene was
mistaken in assuming their engagement would bring Okeke joy.