In the US men were asked to be the head of the family household, protectors, and soldiers. We are typically taught from our families and popular culture to be tough, strong, and resilient.

Men are told not to cry, that showing emotion is weakness. Men are asked to endure suffering quietly.

Women have the appropriate language to discuss what they are feeling and why, thanks to women’s' suffrage and the rise of feminism.

We still feel like the protectors, but women are telling us they don't need protection, so inevitably we start to feel useless. But there aren't many social movements that have addressed a man's role in this new and equal society.

Even among friends a man will be made fun of for showing too much emotion.

Men fear being vulnerable, and in order to share your feelings you have to make yourself vulnerable to another person.

Yes, confessing feelings can make a man feel weak and vulnerable. I often feel uncomfortable talking about my feelings, especially very deep feelings.

That may be the case of no-feeling-at-all. Without any hiding. 

How many men do you know? I dont think you know enough men to come to that generalisation. 

Well... I actually have always been thinking that most often girls are hiding their feelings. -_-