The most common signs of cheating in a relationship include the following: 1. Unexplained absences or secretive behavior: If your partner is suddenly unavailable for extended periods of time, or if they are trying to keep their activities hidden from you, it may be a sign that they are being unfaithful. 2. Changes in physical appearance and hygiene habits: If your partner is taking more time to get ready and making an effort to look good more often than usual, this could be a sign that they are trying to impress someone else.