The wife tells this story, presented in a kind of journal. In short bites - one or two paragraphs - she give her view: her thoughts, anecdotes, and her side of the story. She's not telling the reader about her life, it's more like she's talking to herself, writing notes in her journal, putting thoughts and emotions to the pen. This means a lot is left for you the reader to assume and infer.
She (the narrator-wife is never named) talks about her students and her child, but the book is really more about her relationship with her husband and her internal dialog.