My husband was a serial emotional cheater. He suffers from limerence. He liked the chemical highs that a new romance offers. The brain produces chemicals at the beginning of a relationship that makes you feel euphoric. He liked that feeling. He liked the fantasies and the "what if" opportunities that comes with an emotional affair. He liked the uncertainty and the highs of reciprocation. Each romance never lasted more than 3 years. He had to move from relationship to relationship to continue to get these "new relationship" highs.
He was basically acting like a single man until I found out. He walks the straight and narrow now.
FiveDiamondWife