Signs of a Cheating Spouse:

1) You find birth-control pills in her medicine cabinet, and you've had a vasectomy.

2) Mutual friends start acting strangely toward you. (They either know about cheating or have been told stories about what a horrible wife or girlfriend you are.)

3) Your cheating husband or wife stops confiding in you and seeking advice from you.

4) Sets up a new e-mail account and doesn't tell you about it.

5) He leaves house in morning smelling like Irish Spring and returns in evening smelling like Safeguard.

6) She joins gym and begins a rigorous workout program.

7) She buys a cell phone and doesn't let you know.

8) He sets up a separate cell phone account that is billed to his office.

9) The cheating husband carries condoms, and you are on pill.

10) Begins to delete all incoming phone calls from caller ID.

11) Deletes all incoming e-mails when they used to accumulate.

12) He becomes "accusatory," asking if you are being true to him, usually out of guilt.

13) Raises hypothetical questions such as, "Do you think it's possible to love more than one person at a time?"

14) He buys himself new underwear.

15) He insists child seat, toys, etc., are kept out of his car.

16) The cheating wife stops wearing her wedding ring.

17) Has a sudden desire to be helpful with laundry.

18) Has unexplained scratches or bruises on his or her neck or back.

19) Suddenly wants to try new love techniques.

20) He/she fairly suddenly stops having sex with you.

21) He/she suddenly wants more sex, more often.

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.