We live in a society where men are pictured as strong and powerful. Living in a patriarchal society, our upbringing has taught us that since men have to protect their families, they have to be strong. This idea, if not directly, but in a subliminal way, has taught us that men have to be strong and emotionless. Boys at a very tender age are taught to suppress their emotions; they are told not to cry because nobody like to see a boy cry.
Every boy has heard these at some point in his life, all of which has led him to suppress his feelings. Not showing emotions is a part of the opposite gender roles assigned to men by society. Gradually, boys start to negate their feelings. Women and men, both, have the same emotional range.
The fact that makes the idea differ in both the cases is that women, all the way from their childhood, are allowed to express and show their feelings; because for weird reasons, they are considered weak.
Men are supposed to be the strong and dominant ones, which is why it is not applicable for them to show their emotions.
What we need to understand is that crying is not a sign of weakness; it is a way to express oneself. It makes you stronger, and helps you stand back up fervently for a fight. Bottling up feelings leads to higher chances of disease.