CGP grey did a video on it: https://www.youtube.com/watch?v=iHzzSao6ypE
Basically one car breaking too much will make the following brake even more and so on until one stops and there’s a jam. There is no clear reason like a road blockage or an accident, just compounding slow down.
I asked a therapist the same question and they said: “the problem is you are costantly trying to find a solution for a problem that doesn’t have one, if you are feeling down, sometimes there really is no other solution other than waiting, processing and coping. Take your time if you are not in a crisis and let it pass through”