I was stationed in Berlin from 1974 to 1977 as a 20 something young man looking for female companionship and finding few in my age group. At the time I put it down to the fact that West Berlin was isolated in East Germany surrounded by the Wall. We soldiers called West Berlin, “The St. Petersburg (Florida) of Germany.” A large scale retirement home.
I can see now in retrospect that the problem was common to Europe in general.
Now that you mention it, we weren't exactly swamped with attractive, 20-something female companionship, either. The locals were mostly in their 40's or older, it seemed.