Few feelings are more painful than the suspicion that your husband is cheating on you, especially when you're not sure you can believe him when he promises that he isn't. To determine if your husband is telling the truth about cheating, observe him with an open mind and compare his body language when you know he's telling the truth to his body language when you ask if he's cheating. Obvious differences may indicate that he is lying.
Examine his usual body language. Watch your husband while he talks about things you know are true. Usually, people telling the truth are relaxed and may use hand gestures freely. They will make regular eye contact, but may break eye contact in order to remember something better. Keep mental notes of your husband's usual body language and daily routines so you will know if something changes.
Watch his eyes, especially when you ask him where he has been. According to Truth About Deception, most people look to their left while accessing actual memories and to their right while making up stories. While not foolproof, this method may indicate whether or not he is keeping his true whereabouts from you. Remember, however, that left-handed people may look in opposite directions, since some left-handed people appear to store memories in different places in the brain than right-handed people.
Listen to how he speaks to you. According to the Family Dynamics Institute, a cheating husband may stop talking to you as often as he did before. He may stop confiding in you about his fears or frustrations. Also, his speech patterns may change when he is telling a lie about cheating. For instance, people telling lies will often stop using contractions such as "wasn't" or "can't" and instead will use whole words, such as "was not" or "cannot."
Keep track of his routines. Is he going to more meetings than he used to or staying at work longer than he used to, but there isn't a special project and he hasn't been promoted? When you get home, has your husband taken a shower or brushed his teeth for no apparent reason, which he wouldn't do normally? Are things out of place in your bedroom? While any of these signs can be innocent alone, taken together with other signs, they may indicate a cheater.