What I loved best about that episode of Buffy was the ambiguity. It's awfully convenient to imagine this is due to some drug in the Buffy-verse putting her into the asylum-verse, but there was no concrete proof that the asylum wasn't real. Buffy reacted to it as a standard heroine would, immediately rejecting it, then seeming to be fooled by it, but instead of coming around again and realizing it was fake (if it was), she decided just to choose a life, and she chose the one she knew, the one where she had, as you say, too many responsibilities to abandon it. Her saying goodbye to her parents is really sad at the end because there is that hint that she could have stayed there and it might have been a real happy ending. But, for her friends, and hell, for us, she went back to being the vampire slayer.

Sigh. I need to rewatch Buffy, I guess. It's been a while.