Talk to your partner

Speaking as a psychologist, cheating is a sign of some instability in the relationship. One partner feels as though there is something vital lacking. Cheating, however, need not break couples up. In some cases, it helps to bring forth issues that were previously unspeakable or taboo in the relationship. This is not a justification for the act, mind you, but cheating is a symptom of a deeper problem that may not be addressed openly. I encourage you to speak with your partner about sexual desires, fantasies or even feelings of confinment. Try to be open and receptive to them while sharing your desires as well (honesty is important.) This helps build intimacy and trust. Moreover, it will help you understand why they feel distant or seek other sexual attention. This can both heal and break a relationship... but at least it will be honest.