By Kate Lehrer. Shaye Areheart. 279 pp. $24

In the dark ages of women's novels, a girl had to choose: dutiful wife and mother or passionate lover. As The Bridges of Madison County taught us, the noble thing was to vote for shackles and fondly remember the freedom of true love -- following your heart was simply too dangerous.

But women are evidently either braver now or, as the buzzword suggests, more actualized -- or at least have spent enough time in the workforce to seize the same opportunities for extracurricular sex as your average married man. Kate Lehrer's whimsical fourth novel, Confessions of a Bigamist, is an entry in a burgeoning category of chick lit: women having it all. This long-wedded heroine doesn't just take a lover. She marries him -- and manages not to get tripped up in the deception.

Michelle Banyon, the 47-year-old wife of a successful Manhattan lawyer, maintains her own demanding career as efficiency expert Daisy Straight, a columnist and inspirational speaker who specializes in banishing clutter. Childless after a tragic miscarriage, Michelle and Steve have a crisp, companionable, somewhat soulless marriage. "I was a woman of moderation," Michelle says. "A militant moderate, I used to call myself before realizing that part of me did long for a more extreme, more intense experience."

Enter Wilson Collins. They meet cute, when Michelle runs over him with her rental car while on a lecture tour in Dallas, Tex. She stays a couple of days to help nurse him back to health on his farm in nearby Rollins and winds up falling in love with the strapping, lusty, nature-lovin' dude. Conveniently, her dapper hubby is on an extended business trip to Hong Kong, and Daisy Straight is planning to open a Dallas office. Rechristening herself Mickey, Mrs. Banyon sticks around to enjoy the sexual services of the man who, she gushes, "brought me to climax three times before attending to his needs." He is equally enthralled with her -- "a wild tiger in bed and a sweet kitten out," he marvels -- so much so, in fact, that he insists on making their union legal.

Lehrer's account of the courtship is routine stuff, told in language that could kindly be called unpretentious. "I never contemplated adultery," Michelle says. "I stayed on the straight and narrow, not giving my virtue a thought, blinders in place." Eventually, however, "I needed how Wilson made me feel -- sexy and special. I needed him. On some level I felt I deserved him, and whatever contortions I had to go through seemed well worth the price." Achieving the right tone for this kind of material -- fun, but not utter fluff -- is difficult. (For the record, the mother of all having-your-cake-and-eating-it-too novelists may be the late Laurie Colwin, whose work is now enjoying something of a cult revival.) Lehrer's tone is mostly droll. There are some amusing Hollywood movie moments as Michelle juggles her identities. When she suffers a meltdown and escapes to her sister's suburban house to unclutter her own psychic space, the novel turns a tad sanctimonious. "No one really knows who I am," Michelle sniffs.

Lehrer neither makes the two-marriage gambit plausible nor milks it for enough antic plot twists. Although Daisy Straight is supposedly a visible franchise, nothing about her family status has ever appeared in print that an enterprising Texan -- say, one of the women vying for Wilson's attention -- could unearth. Wilson begs to attend her lectures but, fascinating though he finds her, never thinks to Google her. The intriguing comic possibilities of a prominent woman getting away with a dual life aren't really explored. Lord knows that people with busy schedules and handlers and even bodyguards have thought they could slip into secret lives, even in the Oval Office.

Lehrer has more of substance to say about the rift in her heroine's heart, between the successful East Coast urbanite and the down-home Texas girl. Herself a transplanted Texan, Lehrer explored this subject in depth in her novel When They Took Away the Man in the Moon. Michelle's affection for the rhythms of Texas life is authentic and contagious. Too bad she needs to acquire a whole other husband to enjoy the pleasure of rolling okra in cornmeal. *

Lisa Zeidner is the author of four novels, most recently "Layover." She is a professor of English at Rutgers University in Camden, N. J.