I have been dancing for 2+ years and what you discuss here is part of a larger issue.
Women who don't mix!! I am a single guy and (I'll admit) I took up ballroom dancing mainly to meet women. All the time and money (private lessons) that it still takes, is worth it if I get to dance with lots of women at social dances. Notice I said social dances. That's how they are listed, people are supposed to mix.
Imagine my frustration when I see a lady at a dance I really want to dance with, but noooo she just dances with the same guy all evening. I know not to approach her if I see that. So I wait, and wait, but to no avail.
I have also had the experience of women (professional dance instructors, usually) telling me they can't dance with me because they are "working", which means they are paid escorts for that one guy for the evening.
And so I watch them glide across the dance floor, wondering what would it be like to be with them, but well aware that I may never know. As the poet says "So near, but yet so far".