I think part of the issue is shows like Law and Order: SVU which make every 40 year old male in NYC a sex pervert. Then, the over-saturation of shows like “To Catch a Predator” and “America’s Most Wanted,” coupled with movies that show violent rape like “Last House on the Left” and high school/college seminars, and by the time some women are 20, they are petrified that every guy on the sidewalk is gonna sexually assault them.
Not to play devils advocate, but it is a given in social psychology that because men and women are wired, and socialized differently, when a girl is even kind to a boy, it almost immediately is perceived as a come one, leading to the off repeated “I only like you as a friend.”
Therefore, a lot of boys, often misread girls, and make an advanced based on what they perceive to be a receptive girl. Girls, like you have said, are probably in turn over sensitive to that, and get creeped out more easily.
I managed a business with about 25 employees for a few years, and I had to have frequent talks with the boys, and sometimes girls (well, young men and women) about this very thing. The boys would be friendly, the girls would fraternize back, and it would turn into a big giant mess. And I would have to explain this fundamental difference in social thinking. It almost always worked out, but with one girl who had very bad anxiety problems (she would often break down at work over being busy and be found crying on the ground, or go to the restroom), so I don’t really count that.
It was always a nice refresher to work with the adult women, married, and with children, because they didn’t perceive a wave hello as a sexual advance, and the younger guys (usually), didn’t have the hang up of thinking the married women were into them.
Men and women are fundamentally different, and until people stop being indoctrinate otherwise, these problems will only get worse.