I do not necessarily believe that we are “all wired for affairs” but found this information interesting.
The unsuspecting jilted spouse usually senses a problem when an affair begins. For one thing, an affair usually takes up quite a bit of time, and all sorts of excuses are given to be away from home — having to work late, impulsive trips to the store and unexplained absences from work — they all become more and more difficult to believe. Telephone records and credit card receipts are carefully hidden, for if they are found, they will often reveal the scope of the affair. When the spouses are together, an emotional distance usually prevails. Sex is almost always a problem for women who are having an affair, and many men having an affair find they cannot make love to their wives, either. In many cases, intimacy in marriage becomes so bad that a separation is requested to “sort things out.” An affair is often suspected by the jilted spouse, but almost always vigorously denied by the offending spouse. It usually takes solid evidence… to get an unfaithful spouse to admit the truth. I’ve seen so many spouses lie about affairs, that when one spouse wants a separation, my best guess is that he or she is having an affair. I’m right almost every time. Why would anyone need to be alone to sort things out? It makes much more sense to think that being separated makes it easier to be with their lover. Granted, there are many good reasons for a separation, such as physical or extreme mental abuse. But of all those I’ve seen separate, most have had lovers in the wings. Since an affair usually creates emotional distance between spouses, lovers describe their increasing dissatisfaction with their marriages. They talk about how incompatible they are in marriage and how compatible they are with each other. The addiction they have for each other turns the relationship into a passion that makes an eternal relationship with each other an absolute necessity. Many would rather commit suicide together than to return to their horrible spouses. “Coping With Infidelity” by Willard F. Harley, Jr., Ph.D http://www.marriagebuilders.com/graphic/mbi5059_qa.html
“A love affair is like a short story– it has a beginning, a middle, and an end. The beginning was easy, the middle might drag, invaded by commonplace, but the end, instead of being decisive and well-knit with that element of revelatory surprise as a well-written story should be, it usually dissipated in a succession of messy and humiliating anticlimaxes.” – F. Scott Fitzgerald