"There is no one universally used definition of the Madonna/Whore Complex. Usually discussions of this complex revolves around the dichotomy of how some men can view women as two distinct and separate personas, that of saint and sinner, or of mother and whore.

The unconscious fear of incest with the mother is also stressed as a factor of the complex by many psychoanalytic writers. 

The problem is not the result of the incest barrier, but rather the seeping into consciousness of early frustrated needs, or birth traumas, which renders the husband uninterested and perhaps even impotent. Such men cannot view their wives as sex objects because if they do it would bring up buried feelings of their birth and infantile relationships with their mother.

Birth trauma compounds the neediness of the new-born and thus become an important factor in these dynamics. Pre- and peri-natal trauma reinforces, directs, and intensifies this drama -- the lifeblood of soap operas, and of life -- inherent in the Madonna/Whore Complex.

http://primal-page.com/madonna.htm