That's the real goal of feminism/progressivism, getting the girls to let you. If modesty and virginity are undermined, women are relegated to sex objects and mere property.
It's no irony that the rights women struggled for through all of human history are being lost with their full and enthusiastic consent.
It had to do with the chemistry between 2 young people and the filter religion and society may put on it.
Remember we are talking about 1963 not now. Feminism was the wet dream of the left which was not making that much headway at that time.