First Time

If someone cheats on you, they will do it again.

The first time is always the hardest for the cheater because they won't know what to do. They are not sure of cheating, they don't know what will happen next, they won't know if you or someone else will catch them.

They'll do it again after knowing what happened the first time so they can control better the situation.

It's like skipping class for the first time and you are afraid of teachers finding out, of being caught in the act, of someone calling your parents.

If nobody discovered that you skipped, the next time you'll remember what you did in order to not get caught and not be as scared of skipping class.