Is this because they too would tear up as kids when they got angry?
For myself it was the fact that I would loose control and want to destroy things and become violent. That's how I learned that men express anger. I never saw my parents fight I saw them loving most of the time the only negative emotions I would see would be my father loosing control of his anger at inanimate objects but knowing his history other men were often included.
I had very little idea of how heathy conflict works in a relationship, the idea that anger equals a loss of control and the expression of masculine anger is the use of physical power. Conflict is very stressfull becasue I am trying to control an anger that I feel will become destructive. What on the surface may look like passive behavior is in many ways a fear of my own power.