People tend to cover their eyes and faces with their hands when they cry. You’d think they were hiding from being seen. But I realized recently that I do this privately too, when there is no one watching. I bet a lof of other people do it as well.
I googled “why do people cover their eyes when they cry even when they are alone” – and several other variations of the question – and found only responses to why people cover their faces in front of others (which isn’t hard to guess).