Let's look for a moment at this issue outside the box of political correctness.
Connie and her girlfriend could have each registered to go to the prom as single attendees. They would have still been able hang out and dance together.
But no, that wasn't good enough. They wanted to be registered as a couple, probably to make some kind of political statement. When the school said no, they went and involved the ACLU.
The ACLU threatened the school with litigation they knew the school could not afford. The school board had a choice. Succumb to the strong-arm tactics of the town bully, or maintain their established protocol and shut down the prom. They chose the latter, and I have the utmost admiration for them doing so.
As a result the prom was ruined for all the students. The blame now properly rests where it should. On the shoulders of Connie McMillen and the ACLU. They will now be looked upon as the scourges of the town.
Sometimes justice actually does prevail.