People Develop, People Change, People Behave Differently Over Time

We have a strong belief that character is a major determinant of behavior. Research has once asked a couple of hundred couples to write down every evening for a couple of weeks how considerate or selfish their partner had been. And then I had them predict how their partners would behave the next day. We don't account for the fact that people develop, people change in priorities, people mature, and that they behave differently over time.