What destroys most relationships is not the act of cheating but instead the act of lying about cheating and that goes for either partner. Most people who say they have a problem with cheating actually have a problem with communication and trust.
Either partner can be "caught up in the moment" and do something that would be considered cheating by the other partner, but it becomes a "big deal" when a "mistake" is used to devalue an entire relationship and the person who did the mistake.
People are human, mistakes happen, and every religion teaches forgivens and acceptence.