Can you ever not cry when you're sad?

"Can you ever not cry when you're sad? My heart is so full, but nothing comes out. But when I'm asleep, I shed tears without my knowledge."

Was watching Gunslinger Girl Il ~ Teatrino ~ ep 8 just now, the whole episode is about Claes. What does it felt to think and act because of a person but at the same time not knowing this person existance? Everything she does and thought is about him, but she doesn't have any memory of him, the only thing left, is that nostalgic feelings.