Homer, unaware that it is Marge's birthday, rushes out to buy her a present at the Springfield Mall. He finds a bowling ball and decides to buy it for her. During the night of her birthday dinner at Singing Sirloin, Marge is happy with the kids' presents of French perfume from Bart and a macaroni and glue card of her as the Mona Lisa from Lisa. However, she is deeply offended by Homer's gift as it is another demonstration of his thoughtless gift giving history, and her sisters, Patty and Selma sit by smugly. To make matters worse, as he presents his 'gift', it falls out of his hands and squashes Marge's birthday cake. Deeply resentful with Homer for ruining her birthday again, Marge reminds him that not only has she never gone bowling in her life, but the ball is also inscribed with his name on it.
Realizing that Homer only bought the ball so that he could use it himself, she is determined to learn how to bowl to spite him. But Marge has trouble how to until she meets a French bowling instructor named Jacques, who offers to give her lessons. Jacques proves to be a patient and charming instructor - the opposite of Homer in every way. When he asks about the name inscribed on her ball, she tells him that Homer is actually the ball's name, neglecting to mention that she is married. Homer is faintly aware that something is wrong, but is unsure what is happening. After having passed several bowling lessons, Jacques and Marge agree to meet each other for brunch.
Their brunch goes well until they run into Helen Lovejoy, who seems delighted to not find Marge with Homer. After deflecting Helen's interest by pretending to discuss bowling theory, Jacques asks Marge to meet him the next day away from the gossips of the world at his apartment, causing Marge to faint. In her dream, she imagines a romantic fantasy where she dances with Jacques in his luxurious, bowling-themed apartment. When she comes to, she accepts the invitation.
At home, Homer finds the personalized bowling glove given to Marge by Jacques and realizes he may be losing her. It is not long until Bart realizes that Lisa's suspicions are proving to be true about their parents drifting apart and offers Homer some advice in keeping his mouth shut so it does not get worse. At work the next day, he cannot bring himself to eat the sandwich she made for him, saying that it is all he has left of her. Marge leaves for her meeting with Jacques, but finds herself reminded of lifetime commitment throughout the drive. She comes to a fork in the road, one way leading to the nuclear plant, the other to Jacques' apartment. After an agonized hesitation at the crux of the decision, she surprises Homer at the plant and kisses him warmly. An ecstatic Homer abandons his work post to carry Marge away in his arms. His co-workers want to know what to tell the boss. To the sound of their cheers, he says to say that they are going to the backseat of his car and will not be back for ten minutes.