What is the Prologue of The Merchant's Tale about ???
The Merchant tells the tale of an old knight who has had enough of gallivanting round dating ladies and wants to settle down and get married. He is relatively old at sixty but of course wants a fresh young bride! Sadly, after finding her he loses his sight and perhaps stupidly sends her to comfort a much younger lad - and the two youngsters fall in love and have an affair as they know he cannot see them. The Gods then give him his sight back just in time for him to see them and catch them red-handed. They also give her the defence that she only did it to test his sight as a 'cure' for blindness and all ends well except for the non-stop grumbling about the fickleness and unfaithfulness of women.
The Prologue to the Merchant's Tale is quite short and is a complaint by the merchant about how much he hates his wife and how much he hates being married.
He claims that his wife is worse than a "fiend" (like a demon or a devil). He says that if he could have it to do over again, he would never, ever get married. He says that there is no way that anyone could ever be less happy than he is (at least if they're not married).
Amusingly enough, we find out that he has only been married for two months.