This isn't exactly a book about Mary Beton's amorous adventures. But there is a bit of sex in this book, especially if you read carefully. Mary Beton talks a bit about overt sex scenes in literature when she's critiquing "Mr. A.," a novelist. His matter-of-fact scenes are "somehow dull. Shakespeare's indecency uproots a thousand other things in one's mind, and is far from being dull" (6.4). So, for Mary, a good sex scene has to be, well, fecund.
Which is exactly what the book's only "sex scene" is. We put the phrase in quotation marks because it's not a literal sex scene; it's a metaphor about the male and female parts of a writer's mind coming together to produce literature (6.9). But it's hot.