2. Mood swings
Even men are prone to mood swings when they are trying to cover things up in their personal life. If your even-tempered boyfriend is all of a sudden putting you through the ringer with his changing moods, it can often be a sign that he is cheating on you. Find out if there is something else going on that he is not telling you. Are they just stressed with a lot of stuff going on at work? Are they struggling with a family matter and just haven’t confided in you?