Suburban Madness (2004)

Bobbi Bocha, a cynical private eye who says all men cheat, narrates a story that opens in Houston with a blond purposely running over a man multiple times with her car and then cradling his head as he dies. Flash back six months to the too-exuberantly happy Harris family - Clara and David are orthodontists with a thriving practice, a big house, twin boys who love Dr. Seuss, and David's teen daughter Amy, home from college. David hires Lisa, a klutzy, teary, recently-divorced woman, as a receptionist, and an affair quickly blossoms. Clara hires Bocha. Meanwhile, Bocha pushes her own daughter, who's about to get married, to see the downside. An elephant's faithful.