In the novel's opening pages, the women meet up for dinner, and Sarah reveals that she's engaged. Lauren says all the things you're supposed to say, but fails to work up the kind of enthusiasm she knows is expected in these situations. The truth is that she's not that enthusiastic about helping plan Sarah's nuptials — but she also knows their many years of friendship and closeness mandates that she fulfil this obligation.

Sarah makes note of the slight. But she also knows that she'll sound petty if she gets upset about the way Lauren received her good news. So she lets it go, knowing — after 20 years of friendship — that sometimes it's just easier to glide past a problem and on to the next subject. So that's what she does. The rest of the book continues to alternate between Sarah and Lauren's perspectives, moving back and forth with each chapter, as they edge their way closer to the nuptials. The bride-to-be and her best friend align on bachelorette trips, members of their inner circle, rehearsal dinners, and more — but the truth is that the wedding is just a vehicle for Alam to dissect the relationship between the pair.

Because, first and foremost, Rich and Pretty is a book about the ways in which only women can be close to one another, and what struggles can arise from that closeness. It's a relatable subject if you've ever found a rote check-in with your BFF a little grating without really knowing why. In the friendship between Sarah and Lauren, it becomes ever more clear that what Lauren wants is for Sarah to stop holding her to a version of herself she's trying to leave behind; she is sick of how her longtime friend projects their past onto the present, and wants to be able to act as she pleases. Sarah, on the other hand, finds comfort in the predictability of their friendship. Combined, their perspectives make for a lot of tension.

In one especially telling scene, Sarah and Lauren stay up all night during the bachelorette weekend getaway, slipping into a teenage routine of snuggling up together and breaking into the minibar — content just to be hanging out and laughing. But not so long after that, Lauren has sex with a member of the hotel staff — and Sarah is just appalled. She comes to Lauren's room, furious not just that her friend has done something she considers beneath her, but that she, Sarah, had to find out about it from someone else. It's emblematic of a particular type of jealousy between women: It's not that Sarah has some sexual claim over Lauren, or even that she's prudish. Her frustration stems, she says, from the fact that it was supposed to be a girls' weekend — a time when women focus on each other and leave men out of mind.