What happens when two self-described sex fiends tie the knot? That's the subject of this broadly comic ninth novel from Nichols (The Milagro Beanfield War, 1984, etc.) Birds do it, bees do it, and newlyweds Roger and Zelda do it whenever the mood takes them, up against the refrigerator or out among the garbage cans. Though both are middle-aged, previously married and parents of teenagers, they have the sexual energy of, well, teenagers. But while everything worked fine during their courtship (``a lighthearted commuter affair'')--when both had other partners by mutual consent--marriage is another story. The problem is Zelda's jealousy, which begins on their wedding night (``Is it better with me than it was with Christie?'') and never lets up. Phone calls from Roger's ex-wife Bonnie and letters from his ex- girlfriends send Zelda into wild temper-tantrums; even his daughter Kim becomes a target (``watching you two together is almost like observing incest in action''). Roger reacts wimpishly, offering feeble resistance, trying to meet his deadlines (he's writing a profitable series of intergalactic detective stories) and knowing that Zelda's frenzied outbursts will be followed by even more frenzied lovemaking. Yet both the sex and the anger are mechanical: instead of the dynamics of a credible marriage, Nichols gives us two people on a sitcom treadmill, in a framework of strained bonhomie (``Get this, folks'') and hyperbolic imagery (``Zelda could shut down her ebullience...as emphatically as Fat Man had shut down Hiroshima''). He wraps up their first six months with a knock-down-drag-out fight, a reconciliation, and a too-cute peek into the future. Nichols is evidently in a slump; for all the effort, this is as unerotic as his last novel (An Elegy for September, 1992).