Simon Sharer, 40, married, with a small son, is a city-planner in 1970, fresh from a disaster in Chicago (the residents stoned him when he got up to explain his ideas). His redemption, his next project, turns out to be Sarah Geist, a travel agent whom he meets and begins an affair with. Lovemaking in her apartment. Eating in Chinese restaurants that none of Simon's friends would ever frequent. A trip to Europe together--in France, in Venice, with Sarah slowly revealing bad psychic scars: a drug problem; her half-marriage to a Jewish camp survivor (now a sculptor); suicide in her family; her fragility of spirit and expectation, which Simon's project-making set of mind alternately inflates and flattens. Then, however, back in New York, the affair dwindles--Sarah having fallen in love with one of Simon's friends. And Simon, in physical pain (a wrist injury), puzzles over the interface between public and private happinesses. What is remarkable here is how Stern (The Suicide Academy, Final Cut) expands Simon's amorous education: the prose seems to become richer in direct proportion to Simon's awareness of the difficulties of real love. Less good is the character of Sarah herself--too gauzy, out of reach--and some of the narrative devices (Simon's wife, a professional, is always conveniently flying off on trips; Simon regularly confers, mawkishly, with a dead friend). Yet even at its most obvious--like the ending, with Simon as the wheelchaired ""king of the recovery room"" after surgery on his wrist--the novel is sufficiently invested with insight and delicacy to make it often quite moving. Simon's taking on Sarah, and love itself, as yet another project, then his losing her to her unchangeable past: this seems to be the keystone here, and it's very, very fine.