In Buchi Emecheta's novel Second-Class Citizen, suffering usually arises from some kind of oppression. Let's examine this in more detail.
Adah, the protagonist, has always had big dreams. She wants to go to college and live in the United Kingdom and become a writer, but these dreams are often smothered. Naturally, this causes Adah significant suffering. When her parents don't want her to attend school because she is a girl, she struggles with that until she decides to go anyway. When she must change schools and work in her uncle's house, she suffers again because her extended family treats her like a mere servant.
Adah marries Francis Obi, thinking that this union will bring her more opportunities. For a while, it seems to. Adah gets a good job and manages to hold on to her dreams. But when Francis goes to study in the UK, his parents do not allow Adah to go with him. They need the money she brings in from her job. Again, Adah suffers because someone else is calling the shots and holding her back from what she longs to do.
After a while, though, Adah does go to Britain to be with her husband, and here, her suffering intensifies. The family lives in a tiny room because they are not welcome most places due to their immigrant status and race. Adah cannot find proper care for the children, and their son becomes sick. Francis, too, has changed. He is both lazy and demanding. He is failing at his studies and expects Adah to go to work to support the family while at the same time having more children. Adah learns what it means to be a second-class citizen, and this brings a great deal of suffering. Finally, she leaves her husband, who has taken to beating her, and strikes out on her own, determined to make a better life for herself and her children.