The concept of narcissism is used in evolutionary psychology in relation to the mechanisms of assortative mating, or the non-random choice of a partner for purposes of procreation. (sciencedaily.com)
As a consequence of an over-developed sexual urge we seek sex apart from its primary purpose of procreation. (faith.org.uk)
We fear that he reduced sex in marriage to a function, a tool, and speaks so highly of the primary purpose of procreation that he downgrades and devalues the relational intimacy and bonding through sexual intercourse. (faith.org.uk)