Money plays a crucial, foundational role in Sally Rooney’s novel Normal People. The two main characters come together because of economics and the concomitant differences in their class status.
Connell’s family does not possess the financial resources of Marianne’s family. Her family has much more money, which is why they can afford to pay Connell’s mom to clean their house. Since Connell regularly picks up his mom from her job, Connell has interactions with Marianne that he otherwise wouldn't have had due to the fact they don’t socialize during school. These flirtatious encounters eventually produce a tangled, dramatic romance, which provides the basis for the rest of the narrative.
After high school, Connell and Marianne wind up at Trinity College together and rekindle their relationship. Things are going relatively well until Connell discovers that he won’t be able to stay in Dublin for the summer because the job he had won’t be available. If Connell had greater financial resources, he might have, like Marianne, been able to support himself without a job. Alas, Connell’s lack of money, coupled with his fraught inability to ask Marianne if he can stay with her, leads to their break up.
The economic differences between Connell and Marianne also provoke additional torment from Marianne’s brother, Alan. Connell’s lack of money gives Alan another thing to bully Marianne about.