The Simpsons season 19 episode 7
Episode title: Husbands and Knives
Marge opens a gym for real women because she's disenchanted with Springfield's snooty, glitzy L.A. Body Works. Her gym, Shapes: A Gym for Women, is a huge success, launching a chain that makes Marge rich and famous. But Homer fears Marge will leave him for someone more attractive and goes to extreme lengths to try to save his marriage.