It's bad to go back on a promise.
Julie arranged to pick up a friend from the airport, but found out that her new boss is hosting a happy hour at the same time.
Julie wants to make a good impression on her boss.
Julie tells her boss that she has to pick up a friend from the airport and says that they should plan another happy hour soon.
Julie decides to go to the happy hour instead and texts her friend that they can find a cab after they land.
Julie's friend is grateful that she picked her up, and Julie's boss is happy to move the happy hour back a day.
Julie's friend has to pay a lot of money for the cab ride and is too angry to meet with her later that night.