To some people, cheating means infidelity on the sexual level -- or actually having intercourse with someone who isn't your partner. To others, having an emotional relationship with someone outside of the marriage or partnership is also cheating. In a study on infidelity in the Journal of Marital and Family Therapy, psychological researcher Olivia Leeker and Al Carlozzi, professor of counseling psychology at Oklahoma State University, Tulsa, found that women had stronger emotional reactions to both emotional and sexual cheating than men did. That said, a separate study in the journal Psychology found that both men and women had higher levels of psychological stress reactions to their partner having sexual intercourse with another person than less intimate sexual acts or emotional infidelity.

The cheater is often left with shame, defensiveness and confusion after the affair, writes psychologist Susan Heitler on the Psychology Today website. The cheater needs to move past the defensive stage and acknowledge his actions before any type of emotional healing can take place. This also includes looking inward and understanding why the affair happened. Following infidelity, the cheater may experience powerful emotions of self-loathing that can stop this process from happening. These include guilt, embarrassment and even depression, according to the article "Facilitating Forgiveness in the Treatment of Infidelity: An Interpersonal Model" in the Journal of Family Therapy.

The first stage of psychological distress after discovering that a spouse or partner has cheated is typically rage and shock, writes Heitler in her article "Recovery From an Affair." This may leave the person who was cheated on without the ability to clearly express her feelings or rationally think about the situation at hand. As the shock wears off, the cheated-on partner will eventually begin to process what has happened.

Even though working through infidelity and discussing how it has affected the relationship is possible after the initial shock fades away, lasting effects may linger or eventually end the partnership. The psychological trauma of cheating often results in the couple splitting up in the year following the infidelity, writes social worker and sex addiction specialist Robert Weiss in the article, "One Cost of Multiple Betrayals and Infidelity: Divorce," on the PsychCentral website. Couples may find it challenging to work through feelings of hurt, betrayal and mistrust. While a professional therapist or counselor can help, the couple may need to consider separation.