Using this same logic, no child would ever have to do a PE/sports lesson ever again — or attend any lesson that makes them feel uncomfortable in any way whatsoever. The problem with attempting to base objective societal rules on subjective feelings about things is that when subjectivity becomes the only reason to break the social contract, anything can (and will) be used to break the social contract. I’m not going swimming/doing sports/going to assembly/singing/going outside because I don’t feel like it, and my feelings on the matter can overturn the rules (regardless of what those rules are)

In this instance — it would be better to ensure that children of both sexes are encouraged to ask ANYONE to dance and to try and ensure that everyone participates in a way that feels comfortable. The less fuss is made about the genitals of the participants involved, and the more emphasis is placed on successful and consensual human interaction the better. This is a slightly different argument to the one you have posited.

Giving people the power to veto doing things that make them feel uncomfortable is not the answer — in the long run nobody will do anything that they feel even slightly uncomfortable about, we will create a generation of incapable humans. Making sure everyone understands the implications of both asking (and conversely rejecting) an offer and encouraging discussion between these children is the answer.

From a purely participative point of view actually asking the teenagers to come up with and vote on their own rules is probably the best way to make headway. The discussion might get heated but the centre ground kids (who want to dance and explore their sexual rules) would probably win out. Outliers would either stay at home or they’d be socially ostricised.