What have you done with the Goths?

Party. Bella won't come join the entire time, it was cold out, too. The ending was soon, so everybody walks to the porch for goodbyes. Bella suddenly walks up to the center of the porch, drops dead. :'(
EDIT: Once brought her to the pub on a cold night, different save. She napped on the bench. Woke up, dropped dead. Totally killed the mood, not inviting her out again...