Girl lives happily with boy. Boy has affair. Girl gets mad, then forgives him--in this umpteenth contemporary-lifestyle novel by Jaffe (An American Love Story, 1990), etc. Olivia Okrent was always considered the rebel of her extended Jewish family--the wealthy owners of a large department store in New York City. Divorced twice before she was 30, Olivia further scandalized her clan by becoming a veterinarian instead of a ""real"" doctor, and hosting her own Thanksgiving dinners instead of attending the family get-togethers at Uncle Seymour's. It came as no surprise to anyone, then, when Olivia bought an Upper East Side townhouse with handsome fellow vet Roger Hawkwood, set up a practice with him on the first floor, and moved in with him upstairs. Roger, a comfortable, unadventurous sort makes matters worse by refusing to attend the boring funerals and bar mitzvahs that comprise Olivia's family life. Still, as the years pass Olivia decides she likes her lover better than she does her relatives and declines to make an issue of it--until she learns that while she's attending family affairs, the now 49-year-old Roger is sleeping with a pretty young stockbroker who willingly partakes in the kinds of sexual fantasies that only make Olivia laugh. Mortified, Olivia still can't quite kick her best friend out--and, after an overnight May-December fling of her own, allows Roger to resume massaging her feet at the fire while the dogs, Wozzle and Buster, nestle nearby. ""We must get together more often,"" Olivia's cousins murmur to one another as they feast on salmon appetizers in various ballrooms and living rooms across America, having already passed on the latest rumors of familial child abuse, homosexuality, and suicide. Readers are likely to echo poor Roger's eternal question: ""Why?"" If the title's a bit of a bore, Jaffe's plot (or, rather, plotlessness) this time out is infinitely more so.