A Fish in the Bathtub (1998)

Sam (Jerry Stiller) and Molly (Anne Meara) are a classic bickering old couple, and their marriage has been 40 years of sparring. Finally, when Sam refuses to move the carp he's keeping in their spare bathroom, Molly becomes fed up and unexpectedly leaves. She moves in with their grown son and starts dating an old friend. The couple's daughter convinces Sam to try to win his wife back and rediscover his own sense of romance.