What is the orgin of Alley vs. Valley? was a letter dropped?

Yes. In the ancient Greece, the term alley was a term used for a woman and her area of attraction. When it bacame strectched to the point of accomodating many entries, they added the letter v to differentiate the two types of women. One being more of a virgin, but when she lost her virginity, the letter v was taken from her and added to alley to describe the woman and her status.
This was the embryo of sexism. There was no male adjective that was used to describe men who had experience vs. men who didn’t.
Over the years, the term alley was meant as any narrow opening to get from point A to point B with the least amount of effort, hence, the reputation of men just getting it done and then rolling over and sleeping. Women are left with a feeling of unfulfillment as the man has just passed through.
The term valley was used to mean any large area where people are allowed to roam freely and as long as they want with the least impact on the area entered. Hence, a woman feeling nothing from this space, wondering what color to paint the ceiling as the man is in the valley.
Interesting to find out where things originate.