Infidelity is more often a symptom than the actual root of the problem. While some people just can't help themselves, more often what happens is one or both are

Infidelity is more often a symptom than the actual root of the problem. While some people just can't help themselves, more often what happens is one or both aren't getting the support they need from their spouse and they start looking elsewhere because of it. Then cheating, fighting, divorce. Not really an excuse, so much as an observation.