Cell phone bills are dead giveaways for affairs. After all, they itemize calls, who called who, when they called, how long they spoke, and if they were trading text messages. Cheaters will definitely want to make sure that you don’t go through the cell phone bill in detail. They may suddenly decide to no longer get paper statements. They may give you some excuse about saving the environment. They may also rush to get the mail and remove the cell phone bills. This is a strong sign that someone is cheating.