Rationalization is a defense mechanism in which controversial behaviors or feelings are explained in a rational or logical manner to avoid the true explanation of the behavior or feeling in question.
In other words we know what we want to be true. Now we have to find a reason why it can be true.
People can not think of themselves as horrible so they make their actions right in their own minds.
When a person does something of which the moral super ego disapproves, then the ego seeks to defend itself by adding reasons that make the action acceptable to the super ego. Thus we are able to do something that is outside our values and get away with it without feeling too guilty.
This is related to our need to explain what happens. Our need for esteem also leads us to rationalize to others.
Repression is a type of motivated forgetting in which painful memories are blocked from consciousness awareness. People who commit Adultery repress and rationalize many of their negative feelings and they don't acknowledge them.
We must strive to have values that are based on something and then adhere to them.
God Bless and good luck;