Society has presented an image of women as being helpless.
This may have been replaced (to a small extent) in recent years with media stories of rough girls being arrested for fighting, but the overall perception of women remains the same.
When a woman enters a martial arts class, she is taking a brave step into a male-dominated arena.
You will be immediately faced with a whole range of unflattering associations, based purely upon gender.
Many men are reluctant to partner with a woman.
Women are generally considered to make ineffectual assailants.