i think horniness begins with the mind. of course physical
stimulation helps, but imagine u are sick with high fever and half
awake and sneezing and vomitting and all kinds of crap, and someone
more than accidentally touches ur dick, u think u'll still have the
mood for sex? maybe bad exmaple... 
yes girls feel horny too, and yes they masturabate too, perhaps
less than guys, but they definitely do. the wetness is when they
get horny, not they get wet first then horny.
their wetness is akin to ur hardness lar. u feel horny first, or
hard first?