Because no amount of "I love you" can erase the fact that you looked at my worth,weighed it against your urge and picked the urge. Cheating isn’t a mistake,it’s a decision. A deliberate, selfish act made while knowing exactly who it would hurt.
for relationships to last you really gotta see your partners point of view of things .and be considerate. And be willing to grow. people can learn from their mistakes it’s all about communication.