When you enjoy dancing with someone so much that you always look forward to seeing them every time you go to a dance, you want to dance with them as much as you can, you have fun around them, and their presence or absence can make or break a night of dancing. The feeling is similar to a regular crush without the romance, like a schoolyard crush.
“I have such a dance crush on Mindy!”
“Have you noticed how many of the girls have a dance crush on Alan? I’m jealous!”