The marriage guru and researcher John Gottman, Ph.D. uncovered a fascinating dynamic that seems counter-intuitive. Statistically, there is an inverse relationship between how free spouses feel to say they are not in the mood and decline sex and the frequency of sex the couple will actually have. Meaning, the less politics and the more each spouse feels a guilt-free ability to decline sex, the more often they actually have sex! While at first this sounds preposterous, it actually makes a good deal of sense when you take human human nature into account. The number one cause of reduced desire and arousal is anxiety. The more anxiety that is introduced into the relationship and the sexual encounter, the less arousal there will likely be. Thus, if a couple can create an accepting atmosphere between the two of them, especially in regard to sexual wishes and demands, including the freedom to ask (within the bounds of tznius) and the freedom to decline without emotional payback, the more "nature will take its course" in the long run.