Understand completely. The way I am looking at the pain of losing someone, is that it is a good thing.
You wouldn't have pain and be scared of losing a loved one if you didn't care about the person and their life mattered.
We are all going to die. Not all deaths we know about in advance and can prepare for. Sometimes we cannot prepare and things just happen.
My suggestion. If you are lucky enough to have people in your life that you care about, make memories with them and don't think about it may end.
As I said. Death comes to everyone. You may go before your loved ones. Then worrying about losing them is a moot point.