It`s not as simple as fantasizing being with someone else in the throes of sex. It`s not pining for a long lost lover or wanting to masturbate over the guy or girl we happened to see on the grocery checkout line. It`s not even that one can conjure a specific lover in one`s mind`s eye that they wish to be with, it`s just that sex with one partner begets a need to have sex with another.
The longer one goes without physical intimacy the harder it is to remember what one is missing; the human mind is an amazingly adaptable organ, after a time we simply do not miss what we are missing. With all the facility available for us to surf the net and dial up any type of porn imaginable, in a very real sense once any of us have been without sex for any long period of time we might not truly ever need it in the here-and-now ever again. But when we are having sex, exercising our libido as much as out cock and pussies, that`s when we want to have more of it, and unless we are building an intimacy based on monogamy-an unnatural state given our need for multiple partners at all times-then we want more sex with different people even if we are having great sex with one person.
It might be a biological imperative in men to search for as many wombs to seed, but for women as well-for all people of any sexual preference-we want to experience sex with a different person even if we believe we are wholly satisfied with our current rlove. The simple attraction we feel to other attractive people who pass us by daily is the beginning rumbling of this urge that once lit by consistent healthy sex with one person won`t die for our ache for another.