We can tell you some classic signs of cheating so you can compare them to your own clues, things like; unexplained or uncharacteristic absences, a sudden change in routine or behavior, mood swings, lame excuses when breaking dates or not showing up when expected, being somewhere other than where you have been told they will be, and the classic sign, being seen with another person by a disinterested third party (i.e.: a friend or acquaintance with nothing to lose or gain by telling you what they have seen). If any of these classic signs match the clues that have triggered your doubt chances are good that you are being cheated on, and that sucks. The inevitable next question - what should you do – has a simple answer. Confront the person with your suspicions and tell them what you know. If their answers seem to make sense, and the relationship has a foundation of trust, believe them and tell them what you need to have change in order for things to stay on track. If you don’t believe the explanations end the relationship, end of story. Stripped down to its core cheating is really about trust and betrayal. If you still have trust in your relationship than you have to believe that your partner isn’t cheating if s/he tells you they aren’t; if you don’t have trust in what your partner says nothing else really matters, bottom line, why would you want the relationship anyway? In the end when faced with the possibility of infidelity and betrayal of trust you must trust in yourself and your instincts and follow the course of action that makes the most sense to you.