Almost everyone would agree that sexual activity with another person constitutes cheating. Beyond that, however, there are betrayals that are harder to define, such as emotional infidelity. Psychiatrist Scott Haltzman explains in his book "The Secrets of Surviving Infidelity" that emotional infidelity occurs when a spouse forms a deep psychological bond with another person and shares intimacies with her. If your husband has started having coffee every morning with the same person it can be a sign that he is forming a bond with her. Also be aware of signs that he's closing himself off emotionally such as talking to you less and refusing to talk about your relationship.

Sexual infidelity occurs when a spouse engages in any sexual activity with a person other than his wife. Signs of sexual infidelity can manifest in two very different ways. If your once amorous husband stops trying to initiate intimacy with you, it could be because he's satisfying his desires somewhere else says marriage and family therapist Sheri Meyers in the Huffington Post. On the other hand, if he usually has a low sex drive and he suddenly can't keep his hands off of you it can be because he's been aroused by thoughts of his new lover warns counselor Elly Prior in her article "Telltale Signs that Your Husband or Wife is Cheating on You."

Modern technology has made it easier than ever for people to cheat. In addition to websites that are specifically geared to partners looking for a secret relationship, social media provides many opportunities to connect with a lover. Both men and women often use social media to keep in secret contact with a potential new lover. Therefore, the way your spouse uses technology can tell you if she might be involved in an affair, for example if she is texting or emailing constantly. If she has changed her password or opened new accounts you don't have access to she might be communicating with another man.

When someone is involved in an affair, his emotions tend to fluctuate. In spite of the prevalence of cheating, the Zur Institute reports that more than 90 percent of people believe having an affair is wrong. This tends to make the cheater feel guilty and he often turns that guilt into anger toward you. If he was involved in a one-night stand, he might become defensive when you ask him where he's been or why he's late. If he's involved in a longer affair, he might become more critical or unkind, deliberately trying to start an argument.

When people are involved in a long-term affair, they often make changes to their appearance. They try a new hairstyle or start wearing new clothing, particularly new lingerie. If your spouse suddenly becomes devoted to working out, it could be because she is trying to look good for someone else. According to adultery recovery specialist Anne Bercht in her article "Top 10 Signs of Infidelity" pay attention if your spouse isn't wearing her wedding ring. Other signs include coming home in different clothes than she wore to work or wearing different cologne or perfume than when you saw her last.