Yawn.
For some reason, the way the trailer was cut and everything it reminded me of a short story I read once, which then got me thinking about how the movie ends.
My guess? Brittany Murphy is already dead. She's been dead for months, maybe some car accident or natural death, who knows. Her fiance, consumed with grief, can't face the fact that she's gone so he convinces himself that she's still alive. The girl he's staking out is just some innocent blonde lookalike. Blahblahblahetcetc