Here's a relatively consistent truth: Among conservatives are the most genetically predisposed to mating and reproduction. Among liberals are the most naturally deselected. Conservatives have been selected more frequently for sex throughout the entirety of their mature lives and have developed mechanisms for dealing with pairing rituals in greater breadth and effectiveness. Conservatives are simply more attractive mates have more experience in such scenarios, both in past and present tenses.
For liberals who are typically less attractive mates on the whole and had less experience with traditional mating selection during their developmental years, sex is more of a novelty and something over which they have less developed screening mechanisms. They require less effective methods to preserve monogamy in their relationships, and they view sex as more of a desireable commodity due to scarcity in quantity and/or quality of available mates during their younger years and throughout their lives. They tend to embrace more licentious views as a result.