I can understand the dancing thing a bit. In the days when it was a general social activity, not restricted to romantic partners, if everyone chose only to accept dances from the "cool" guys (who only asked the gorgeous girls), half of the group would hang around the entire evening doing nothing but envying those fortunate enough to find partners. So, one was supposed to accept ONE (1) dance with anyone who asked. They were supposed to realize that after that ONE (1) dance, they should find someone else to pester. Also, the ritual of "cutting in" was not only allowed, but encouraged. You learned a secret signal for a male friend to come over, gently push the objectionable partner aside, while murmuring, "May I cut in?" and finishing the dance with you. The objectionable partner then had to dance with everyone else before trying again.
So, girls had an obligation to accept, but males had an obligation to keep going the rounds, unless they had a dance partner lined up on a card. People who danced only with their date or other object of desire were considered social clods. It worked when people knew the rules. But it was not applicable to dating (particularly the "cutting in" part).