The old man and the young wife — what's up with story plots like this?
Throughout the history of Western civilization, the idea of a very old man marrying a very young woman, usually 18 or younger, has been a constant source of comedy and the subject of many comic masterpieces. Most often these stories deal with the clever and manipulative ways in which the young wife is able to deceive her old husband.
The basic assumption of this type of story is that if an old man is fool enough to marry someone much younger, the old fool deserves to be fooled. Another characteristic of this standard plot is that the old husband is domineering and jealous and often locks up his young bride or keeps her under such close scrutiny that there is no chance of being deceived. Therefore, the delight of this type of story lies in the clever methods the wife uses to deceive the husband or, in some cases, the "poetic" justice involved in having a domineering husband brought to his knees.
Chaucer explores this theme in a couple of his Canterbury Tales: "The Miller's Tale" (Nicholas and Alison) and "The Merchant's Tale" (January and May).