If there's a love triangle at the center of The Marriage Plot, then it's isosceles—two towering male characters (one autobiographical, one biographical) grounded by one basic female, Madeleine Hanna, about whom, despite her prominence in the novel, we end up knowing very little. She's an English major at Brown University who loves both Jane Austen and Roland Barthes; she's better behaved than her older sister; she's shown, at one point, perched on her dorm room's bed in some kind of pajama, eating peanut butter from the jar with a spoon, looking for all the world like a commercial of a girl hard at work. For much of the novel, Madeleine's work consists of a paper about the use of the marriage plot in Victorian novels, a de facto focus arising from a college course entitled, of course, “The Marriage Plot.” It starts as an assignment, turns into her undergraduate thesis, and is later edited into a published article (presumably by Madeleine, though aside from her peanut-butter bender we rarely see her consult her books for anything but romantic fortunes, and her only use of a pencil comes in the form of a Dear John letter), but through her hours of work on “I Thought You'd Never Ask: Some Thoughts on the Marriage Plot,” those elusive thoughts never really take shape.
What we can glean from the story comes to us in the form of characters defined not by marriage, but by sex—the having of it, the anticipation, and the desire to explicate of it. The novel opens with Madeleine hung over in bed, an enticing stain on the dress she fell asleep in. Two of her previous boyfriends are summarized right away, one of whom would speak only of circumcision, the other of whom she was ashamed to like because of his side career as a male model; she's described at one point wishing he were an athlete or a politician instead, grasping for platitudes of masculinity. At the end of her first date with her future husband, Leonard Bankhead, the syntax contorts to emphasize the fact that they don't kiss goodbye over what actually does happen. Later, or perhaps earlier (chronology is one of this novel's great victims), Madeleine meets the other side of her triangle, a religious studies major named Mitchell Grammaticus, at a toga party, and her toga briefly slips off her shoulder in front of him. Having now succeeded in viewing her breast, Mitchell loves Madeleine, but Madeleine loves Leonard. Leonard loves Madeleine, too, but he also loves the manic effects of his manic depression. Nobody loves Mitchell, except late in the novel when Jesus loves him.