The concept of patriarchal ideology in feminist studies is a very irritating and Puzzling one. If patriarchal ideology is considered to have dominated and determined the whole history of Western culture; not excluding its language and thought, then feminists aiming at overcoming patriarchy face a serious dilemma: even their anti-patriarchal language of resistance is under the sway of patriarchal ideology, thus depriving them of possibility of resistance. If seen as power located in space, time and discourse, on the other hand, feminists again find themselves ineluctably embracing the unwelcome consequence that patriarchal ideology has never been as extensive and universal as they claimed. For feminists in between these two extremes, the task remains for us to find a more satisfactory third account of patriarchal ideology. In this paper I propose that the Patriarchal ideology is universal but works in a self-contradictory manner so that it is vulnerable to criticism Ideology is composed of diverse and conflicting components, thereby never being integrated into a single, coherent and harmonious unity. It is divided within itself. In order to justify and ground textually this concept of ideology as contradictory construct, I examine a medieval chivalric tradition of "Frauendienst" in Thomas Malory`s Morte d` Arthur, which has been interpreted both patriarchally and anti-patriarchally. My reading focuses on the love relationship between Launcelot and Guinevere and demonstrates that Frauendienst is a site where patriarchal ideology is simultaneously confirmed and denied. In the absence of coherent combination of ideologemes, and in the following conflict between their textual meanings and functions, Malory`s text explicitly, sometimes explicitly, criticizes its own ideology: while upholding its own ideology, it turns against itself inadvertently and commits a textual/patriarchal suicide.