Get Out Your Handkerchiefs (1978)

Solange is depressed: she's stopped smiling, she eats little, she says less. She has fainting fits. Her husband Raoul seeks to save her by enlisting Stephane, a stranger, to be her lover. Although he listens to Mozart and has every Pocket Book arranged in alphabetical order, Stephane fails to cheer Solange. She knits. She does housework. Everyone, including their neighbor a vegetable vendor, agrees that she needs a child, yet she fails to get pregnant by either lover. The three take a job running a kids' summer camp where they meet Christian, the precocious 13-year-old son of the local factory manager. It is Christian who restores Solange to laughter

Source: TMDb