You decide you need to apologize to your mate for raising your voice at them. You know that it was inappropriate and was not being respectful. You muster up enough humility to go up to your spouse and say, "I'm sorry that I raised my voice at you. That was inappropriate." If you leave it at that it would be a perfectly acceptable apology! But then you add, "But if you would have listened to me..." Now the apology changed into shifting blame. Shifting blame is easy to do. Even hard not to do sometimes! It is human nature to be the best that we can be. Even when we know we have done something wrong and apologize for it, subconsciously we don't want it to be our fault. Therefore, we start shifting blame.
This is not a new phenomenon. Think back to Adam and Eve in the Garden of Eden...
Then the man said, "The woman whom you gave to be with me, she gave me of the tree, and I ate." And the Lord God said to the woman, "What is this you have done?" The woman said, "The serpent deceived me, and I ate." (Genesis 3:12-13)
They were even shifting blame back then! It is indeed human nature. However, God saw through it and held them both accountable. He does the same now as well. He does not want us shifting blame, but taking responsibility for our own actions.
[Read the rest of the article at Start Marriage Right.]