I want to add one other time in the series when Clark cried. When he and Lois were saying goodbye in the DP conference room before he left for New Krypton, she said, "Don't forget me," and the shot cut to Clark, whose eyes were red, who was blinking rapidly, and who had his teeth so tightly clenched that he could hardly say her name. He may not have been actively crying in that scene, but he was fighting tears as hard as I've ever seen a person do it. Notice that both times we saw him near tears were when he was losing Lois. So I would say that Clark crying (or almost crying) over losing Lois is in canon, but crying at other rare times of deep emotion is FoLCLore, and most FoLC will accept either one as in-character.
