The stop-motion is meant to show us that these girls are so in love that they're turning into monsters, but because the werewolf elements of the story are never explicitly addressed, their effect is confounding.
A girl-on-girl werewolf flick may sound similar to a plot line for the ultimate guilty pleasure horror flick, but in reality Jack and Diane may be just a little too John-Mellan-campy for most viewers' tastes.
Let's see, monsters, internal organs with hair snaking through them, blood, teeth falling out after a kiss, vomiting, suicide over a broken heart. Some people call this romantic and charming. Pardon me while I gag.