There is a little word that is so easy to pronounce but which so many find it impossible to utter: "Sorry". Why are some people unable to apologize? Either they believe they did not do anything wrong (although they did) or they believe that, by acknowledging the fact that they made a mistake, they put themselves down. In the first case they behave as conceited jerks, in the second as self-conscious jerks who are totally lacking in self-confidence.
On the other hand, saying sorry shows that you are smart enough to recognize that you are not infallible (no-one is!), great enough to admit it and apologize for it.