Read the title of your post again. Sounds like someone needs to fukken grow a pair.
She's going with you and she is the luckiest girl at the school because of this, never forget that. You wont dance with other girls as a result of her dancing with guys, it's easy to see whats happening there. Instead, you will take the power and dance with other girls first. If she does dance with other guys, you wont care, you not ****en tied together by the leg.
Most importantly, have a good fukken time and dont spend your whole night analysing ****.