That's rub with the whole 'passage of time' problem. Situations and people and things change. We, you and I and us, can't stop that. We will change. And the situation around us will change, whether or not we ask.
Time continues to march on and sometimes (well, most of the time) we get left in the dust.
Old friendships die. New friendships are born. Most of the time, you lose more friends than you gain as you get older. The older friendships sometimes become more important and sometimes become vacuums. Sometimes you gain friends that weren't as good as the friends that you had, and sometimes you gain friends that are better than the ones you had before.
People grow, like plants, in different ways but always towards the same goal. We all grow towards what we think feeds us. Plants grow towards the sun. Some people grow towards a desire of success, others towards stability, others towards control, others stay on the path of simple pleasure. The thing about growth is that it is, or at least should be, natural.
But unlike plants we don't necessarily grow towards what feeds us, do we? So many times we grow towards what we think will feed us. What we think will satisfy us. Why would we grow towards something that we think would satisfy us, but won't? Shouldn't we, as a species and a society and a sentient race, know better?
The simple answer is, obviously, no. Of course we don't know better.
Because we're stupid.