Jan 19, 2021 According to researchers out of the University of Rochester, the happiest couples all have one trait in common ... psychological flexibility. It sounds complicated, but according to experts it’s about being easy-going, keeping a positive outlook during difficult times, and basically being able to handle change effectively. According to the research, couples who are psychologically flexible “can roll with the changes much easier and deal with the curveballs that life throws at them.” (