Were the World Mine
(2008)

When the openly gay Timothy is cast as Puck in the school production of A Midsummer's Night Dream, he discovers that he is able to brew the love potion from the play. Armed with the concoction, he takes inspiration from his character and decides to cause some mischief by turning the narrow minded townspeople gay and letting them see what life is like for him. Chaos and dance numbers ensue...

In the end, Timothy ends the spell and the town reverts to normal (if a little more open-minded) but to Timothy's delight, the object of his affection remains in love with him even after the spell is lifted.

Thanks Mary C!