Have you ever been with someone who remembers an argument totally different than you do? They might rearrange factual events to suit a timeline that benefits themselves, putting the things you did first so they look like their poor behavior was in response to yours?
This is a form of revisionist history. While traditionally, revisionist history refers to historical events, the term has gained popularity with regard to relationships. It's very difficult to work things through with someone who engages in revisionist history. Sometimes, it even means the end of a friendship. Here's some more on revisionist history as it relates to friendship.