Recent statistics suggest that 40% of women (and that number is increasing) and 60% of men at one point indulge in extramarital affairs. Put those numbers together and it is estimated that 80% of marriages will have one spouse at one point or another involved in marital infidelity.
That may seem like a very steep number. However after two decades plus of full time work as a marriage and family therapist, I don't believe that number is off charts. I worked with a great number of people involved in infidelity who were never discovered.
The possibility that someone close to you is or soon will be involved in an extramarital affair (any of three parties) is extremely high.
Maybe you will know. You will see telltale signs. You will notice changes in person's habits and behavioral patterns as well as a detachment, lack of focus and reduced productivity. Maybe you will sense something "out of character" but be unable to pinpoint what it is.
It is not a given that he/she will tell you. Those hiding affair will continue to hide. The "victim" of extramarital affair often, at least initially, is racked with anger, hurt, embarrassment and thoughts of failing that preclude divulging crisis.
It might be important to confront person with your observations, depending on status of your relationship with person.
It is important to understand that extramarital affairs are different and serve different purposes.
Out of my study and experience with hundreds of couples I've identified 7 different kinds of infidelity.
Briefly, some extramarital affairs are reactivity to a perceived lack of intimacy in marriage. Others arise out of addictive tendencies or a history of sexual confusion or trauma.
Some in our culture play out issues of entitlement and power by becoming "trophy chasers." This "boys will be boys" mentality is subtly encouraged in some contexts. Some become involved in marital infidelity because of a high need for drama and excitement and are enthralled with idea of "being in love" and having that "loving feeling."
An extramarital affair might be for revenge either because spouse did or did not do something. Or revenge may stem from rage. Although revenge is motive for both, they look and feel very different.
Another form of infidelity serves purpose of affirming personal desirability. A nagging question of being "OK" may lead to usually a short-term and one-person affair. And finally, some affairs are a dance that attempts to balance needs for distance and intimacy in marriage, often with collusion from spouse.
The prognosis for survivability of marriage is different for each. Some affairs are best thing that happens to a marriage. Others serve a death knell. As well, different extramarital affairs demand different strategies on part of spouse or others. Some demand toughness and movement. Others demand patience and understanding.