Actually, it goes beyond being "equals" as the previous poster suggests. She contends that marriages are happiest when the woman has the upper hand - and is the boss. This is shown in her tale as well when the knight gets the secret to what women really want from the loathly lady. And it is only when the knight follows that same advice in their wedding bed that he is able to get what he truly wants.
Chaucer uses his gift of gab to help us read between the lines with the "worthy" woman of Bath. He tells us that she puts her social position first...probably why she marries so many weathy men in the first place...but she definitely unleashed her "wrath" if anyone whose social status was not above the Wife's stepped up to the alter before she. She's witty, intelligent, wealthy, opinionated, and sensual (Chaucer describes her as gap-toothed which in the Middle Ages translated to "sex-craved"). Her prologue is a vigorous defense of women that challenges the medieval view that Eve was responsible for the Fall of Man. She tells the reader in her prologue that her husbands mistreated her--one cheated, one hit her, etc. (some critics point to the fact that she is a widow so many times and hint that perhaps the "worthy" woman disposed of those who displeased her)--and so she is in the market for husband number six who will be both her debtor and her slave. This leads her to her tale which supports the moral that woman want to be treated as equals in their marriages.
The Wife of Bath is a very interesting character. She is my favorite character in Chaucer's tales.
The Wife of Bath is a feminist before her time. She is opinionated, strong-willed, and charismatic. She is confident and she does not give in to male-driven society. She has been married 5 times and is hunting for her 6th husband. She is a no-nonsense kind of gal and she knows what she wants and she goes out and gets it. She is determined and motivated!
Her marriages actually reveal a lot about her that is not positive. She manipulates the men she has been married to and extorts money from them in some cases. She uses her physical attributes to get what she wants, as well. She realizes the power of that and takes full advantage of it. She seems to be marrying for the wrong reasons. She might be desperately searching to find that one "true" love and simply compensates by marrying too quickly with the hopes she can change them.
Regardless, her marriages reveal much about her character and her personality.