The point is that adolescent girls do not go to the bathroom to masturbate. Female adolescence involves girls developing the reproductive function required for bearing children - breast development, periods etc. Only boys experience a significant increase in responsiveness at adolescence. This is reflected in their much greater interest in the opposite sex and in all aspects of sex generally. It is male arousal that causes male sex drive. Men are aroused by many more erotic stimuli than women ever are.
Exactly - it is said that boys masturbate in the bathroom. But many also masturbate in their bedrooms if they have privacy there. The male is the most responsive in adolescence.
At adolescence boys see some developments that come along with puberty and they marvel over these developments. That is why they spend more time when they are in the bathroom
Exactly - male responsiveness is a fascinating experience for an adolescent boy. But girls do not have the same experience. Girls get periods and breast development, both of which are linked to their child-bearing role. They do not become highly responsive at adolescence as boys do. In fact, most women are unresponsive throughout their lives. Men's assumption that female orgasm is common causes untold confusion. This is just a male fantasy but a persistent one.