The more accurate statement is that people, like everything else, change constantly - often despite our best efforts to hold on to and to maintain what is familiar (even if it's misery). Change is ruthless, relentless, inevitable. It creates, saves, and undoes us. What causes distress is a more or less rigid attachment to the way things were a year, a decade, a month, or a moment ago.
My mentor reminds me: form or be formed. Adapting to our bodies as they grow (stronger or weaker, faster or slower), adapting to the changes in others, in those we love, the changes in our work-life, and in our world is vital.
Psychotherapy can help you accept the losses more gracefully, evaluate the possibilities more fully, and participate more proactively in the formation of what you might otherwise think is simply happening to you.