Death, disease, old age, friends leaving, jobs lost. People change, situations change. ALL the time. Everything is temporary. Everything, including life itself. Which can be really hard to accept. Some struggle to handle even the smallest changes in life. Why is that?
Because the mind is a bit tricky and has a way of controlling us, if we let it. If allowed, the mind will happily spin out on thoughts of fear and worry about life and all that could happen. Poor me, life is so hard, what if, why me etc. etc.