( inspired by a fairly obscure video game, Love Story )
Here's the thing - you're dead. No matter your precautions or lack thereof, you've reached the end of the line. Rotten luck, huh? Actually, you're one of the lucky ones, because you've been sent back. As a ghost, admittedly, but at least one person can see you.
And that's key. The conditions of your return, both to the mortal coil and, eventually, back to your body, is that you get them, your sole witness, to fall in love with you.
Oh, you also have six days. Easy enough.