Rukmani is the narrator of her own story, which she tells in a flashback. As with any story told in the first person, it’s important to remember that everything the narrator tells is selected for a reason. Thus every detail she includes (like the phrase she repeats to herself as Nathan is dying) and every detail she deliberately excludes (like what exactly Kenny did for her infertility) is deliberate. What Ruku chooses to tell us ends up being a reflection of Ruku’s own values and personality. The events of the story take on an added meaning when we realize they’re excerpts of an entire life. What Rukmani shares with us are those special moments that a dying woman reflecting on her life thinks are important.
This flashback point of view allows the whole story to be Ruku’s own reflections on her own life. She tells us the story as past tense, and she occasionally adds foreshadowing and interpretation that she couldn’t have known at the time. These little "notes from the future" are "present Ruku" interpreting "past Ruku." When they happen, they’re important markers. In regular first-person mode, a narrator is able to tell a compelling and straightforward story. The usage of first-person flashbacks, though, is an opportunity to elevate the simple narrative to thoughtful reflection without cluttering the story itself.