The answer to your question is... probably not. Don't accuse him of it unless you have hard evidence. The easiest way to find out why he erases his phone is (gasp) to ask him. If you're concerned about his hot secretary or the cutie in the next cubicle, chances are he's given you some sign that there are problems in the relationship. If it's just your natural suspicion or your own insecurities causing your worry, make sure you examine your own motivations. Your best bet is to be up front with him. Ask him. Most of us can tell when our husbands are lying. The one thing you do not want to do is accuse him angrily and make him feel attacked. That kind of behavior can lead to him eventually resenting you enough to cheat, and causing a problem where one hadn't been before.