Recent statistics suggest that 40% of women (that number is increasing) & 60% of men at one point indulge in extramarital affairs.
Put those numbers together; it is estimated that 80% of the 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 the 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 extramarital affairs (any of the three parties) is extremely high.
Maybe you will know. You will see telltale signs. You will notice changes in the person's habits plus behavioral patterns as well as a detachment, lack of focus & 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 the affair will continue to hide.
The "victim" of the extramarital affairs often, at least initially, is racked with anger, hurt, embarrassment & thoughts of failing that preclude divulging the crisis.
It might be important to confront the person with your observations, depending on the status of your relationship with the 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 the 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 the idea of "being in love" and having that "loving feeling."
An extramarital affair might be for revenge either because the spouse did or did not do something. Or the revenge may stem from rage.
Although revenge is the motive for both, they look and feel very different.
Another form of infidelity serves the 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 the marriage, often with collusion from the spouse.