A nice idea for an 80's-style Upper East Side comedy of manners fizzles as Cohen clings too rigidly to stereotypes and stale Wasp vs. Jewish humor. The narrator hero, Jamie Greene, 40, is a college history professor, a stylish and pampered boy-man who has a familiar midlife crisis triggered in a clever way. Having left life on Fifth Avenue and his wife Ellen Ornstein, an advertising power. house, to set up shop on Central Park West with a 23-year-old grad student and heiress, Jamie learns that Ellen has become pregnant on their farewell night. Much as he'd like to stay loose and fashionable--living with one woman, fathering a child by another--parental impulses draw him back to Ellen, who plays it cool until the final delivery-room scene. It's a neat premise for light comedy, but Jamie is too cute to engage our real sympathies, and Cohen draws the supporting cast in the outlines of familiar cartoons--Ellen's Scarsdale parents who disguise themselves as Town and Country Wasps, a Fifth Avenue matchmaker who's had a new facelift for every husband. A subplot about departmental politics rests on a wooden joke having to do with the supposed capacity of urban intellectual Jews for suffering. Not until the novel's second half, after Jamie makes his descent into a hellish night of New York club-hopping and returns to Ellen's apartment to serve penance, does the novel generate some true feeling and warmth. Cohen covered similar turf in his first novel (Falling Out); one waits for him to stop taking so many cues from New York magazine and discover something new in monied Manhattan.