What can you expect from a story in which the orthodox Jewish narrator plainly states that his favorite fantasy is having written the Mendelssohn Violin Concerto and performing it at Carnegie Hall? Well, in this case, quite a bit.
The narrator is an orthodox Jewish graduate student who has developed an interest in a young lady (who plays the viola) with an unremarkable rear end, which nonetheless moves delightfully and unselfconsciously, and who keeps a diaphragm case right next to the Bausch & Lomb in the medicine cabinet and a small towel under the bed. It takes him three dates even to get to first bass. That's the only viola joke I know, except for the one about the G-string.
Some of the sex is subtle -- e.g., they quote Yeats and Orlando Furioso while making love, they converse in ottava rima, and they probably would not even understand my great joke about first bass. In short, they relived high school the way it ought to have been. They rut freely without falling into a rut.
Eventually they realize that their sex life is based on shallow things like physical stimulation and intellectual repartee, and so they drift apart. But physical stimulation and intellectual repartee can be a good place to seek vicarious sex on a quiet winter's afternoon.