Cheating itself does not just affect the people involved. It also affects the people around.
Mentally, emotionally and physically, you are hurting. In the times of your hurting, you hurt the people around you who love you too. There are times when you go through the 4 stages of emotions and also the 7 stages of grief/depression.
When people are affected, they gradually lose faith in human mankind. They start to compare their previous partner with their current ones. Sometimes, they fear that the current one might just leave them just like the previous one. It will become so hard just for that single person to commit to another relationship because of the grief caused by one.
When children are affected by divorces that end because of partner cheating. At a young age, they are affected and probably some are influenced that the opposite sex cheats. When they do get into a relationship, they will question their partners and ask them many questions. Security in this type of relationship is at the most top important. Just a small thing will alert them and they will immediately question and ask the partner. Thus many relationships will fail because of stress on the opposite sex and also they might feel suffocated in the relationship. Just sometimes, maybe, they find the right one that assure them and stays by them. But they would still have the insecurities and thus they themselves might cheat on their partners.
It's a cycle one must try to break.