dying alone, being forgotten, fire, heights, and the weather are all pretty reasonable fears
but,
my biggest fear with you is being happy, because I know that it will be life-changing my world will revolve around you and no matter what happens, I'll know that you alone will be enough to sustain me and then one day I'll wake to find that you're gone and I'll be completely lost
and I'm really not sure if I can make it through all that again. You're my everything