Public and ecclesial discourses influence opinions on the institution of heteronormative marriage. The term "discourse" indicates that private knowledge and experiences are made known in the public sphere. Against this background the article focuses on three postmodern approaches to a theology of marriage with regard to the significance or insignificance of the biological difference between femaleness and maleness. The first approach is that of marriage as a linguistic expression of intimacy in a relationship. According to this view, heterosexual marriage is not seen as the only possibility for expressing the intimate relationship between God and human beings. The second approach assumes that love and caring, supposedly inherent to heterosexual marriage, can also exist in other relationships. This implies that marriage as institution should also be available to people in relationships other than heterosexual. The third approach emphasizes marriage and sexuality as being embedded in community. Such a view makes sexual difference and procreation peripheral to sexual ethics. The aim of this article is to suggest a further option for consideration, namely the "de-centre-ing" of sexual difference in the theology of marriage. This postmodern option pleads for a respect for privacy with regard to sexual intimacy, also in ecclesial and public discourse.