Race as a social construction
Ifemelu does not experience race as a fixed identity until America assigns her one. The novel shows race as something societies build and enforce, not something people simply are. Every blog post Ifemelu writes is evidence for this argument.
The cost of assimilation
Every character who tries to fit into a new country pays a price. Ifemelu straightens her hair, fakes accents, and performs versions of herself to survive. Obinze works under a false name in London. The novel tracks what gets lost in those performances.
Love interrupted by circumstance
Ifemelu and Obinze do not fall out of love. They get separated by visa rules, poverty, shame, and geography. The novel uses their relationship to show how external forces break things that are internally strong.
Return and belonging
Ifemelu's return to Lagos is not a homecoming in the simple sense. She is a returnee, which is a category that fits nowhere. The novel refuses to let Nigeria be a safe haven. Belonging, it turns out, has to be rebuilt, not recovered.
Class and aspiration
Almost every character in the novel is trying to move up, get out, or stay stable. Obinze's wealth in Lagos, Ifemelu's fellowship at Princeton, Aunty Uju's life in America: all of them are shaped by the pressure to achieve something that will make the sacrifice worth it. The novel asks whether it ever is.