In her article, the "Warning Signs of Infidelity," Dr. Betty Phillips says that one sign of cheating is when your spouse become progressively defensive or critical of you. He may be trying to hide a lie or is falling for someone else and is pushing you away. Highlighting all of the characteristics that he does not like about you helps him rationalize cheating on you. In his article, "How to Tell if Someone Is Lying," Dr. Matt Moody states that defensiveness, anger and argumentativeness are often indicators of infidelity.

Psychologist Dr. Ella Lasky reports that your spouse may seem more on edge, with an exaggerated alert response. Characteristics of a tense spouse include an apparent unease when you use her phone or computer or ask her for her login information. Depression is also likely as the cheating spouse may be dealing with feelings of guilt, confusion and indecision regarding the affair. She could seem irritable, sad, short-tempered and angry for no apparent reason.

Your spouse may suddenly show concern for his appearance, such as wanting to lose weight or shaving new areas of his body. In her article, "10 Signs of a Cheating Spouse," divorce consultant Dr. Reeta Sommer says that the changes in behavior could also be new hobbies or interests, such as salsa dancing or playing chess, that are notably inconsistent with his usual interests. You may hear him use new phrases or sayings and wonder where they came from. Or he may begin to listen to a new genre of music, such as Country and Western, music that his lover prefers.

In her article, "10 Signs of a Cheating Spouse," Dr. Reeta Sommer says you may notice your spouse leaving the room to call or text her lover. She adds that your wife may begin taking showers immediately upon returning home from work. She may put passwords on her phone or computer to lock the access. These methods are all measures to attempt to increase privacy and hide the affair.

In an article about infidelity, "The American Association for Marriage and Family Therapy" claims that many extramarital affairs stem from platonic friendships that turned into something more intimate. If he has a friend of the opposite sex at work, for example, and feels more comfortable speaking to her than his own wife, he will start becoming more distant and stop communicating with his wife. Sometimes he will begin complaining to this "friend" about his wife or kids. This kind of relationship is termed an emotional affair, and it is usually more hurtful to the partner than a sexual affair.