One of the most common questions I get when delivering “difficult people” workshops is when to give up on those challenging coworkers who can’t or won’t change their behaviors.
Usually, I offer some pointers about what they should say in a certain situation. The person responds with, “I tried that, and it didn’t work.” When I ask people if they tried again, most did not.
That’s why I like this article that suggests you should try at least three times. Then, if it still isn’t working, you have to make a decision about the relationship.