How do you recognize cheater in relationship?

Change in behavior. Sleep schedule changes. Falling asleep sooner than usual, going to sleep later than usual. Cellphone facing down the table when they’re with you. They start acting way too nice to you or too distant unexpectedly . One of these things alone isn’t a stronger indicator of cheating and they also could mean something else, but if they’re doing more than one of those things all of a sudden, you should be aware.