You can't control what others do.
The advice given to me by someone who spent a lot of money on therapy. That second-hand knowledge continues to help me tremendously.
People make their own paths, and while sometimes I think we're all hopping and skipping along the SAME path... someone makes a hard left, and POOF! They're gone.
Sometimes I just want to pull my hair out.
But, life goes on whether I get angry, sad, mad or blue.
So repeat as needed... You can't control what others do.