I would say that people who stay in a marriage might be said to have a healthy sense of aging and moving from one stage of life to the next. They recognize that people don't stay young, that relationships don't stay new but mature and evolve, and that there are long term benefits to commitment. So someone who decides to leave a spouse for another woman, especially a younger woman (assuming that the marital relationship is "normal" not crazy, abusive, etc.), hasn't transitioned from one life stage to the next. He (or she) is caught back in a previous less mature phase of life, is seeking the newness of a romantic relationship, and is reliving a younger age and period of life through that relationship. So it seems to show a lack of maturity, a lack of self-acceptance, etc., perhaps an attempt to re-do those years, to feel younger again.Again, there might be other scenarios - a marriage can be downright bad and sometimes people just click whatever the age - but that's my general take.