First Edit: Dying Alone

[Jana]

Dying Alone

The thought of dying first is killing me.   <- Agree, good opening hook, touches the universal, I'm hearing a potential mate brought in at this point.
I know we searched and found our path, my wife, <- Maybe shorten. Ex. "We've searched and found our path, my wife" or "Together we've found our path, my wife"
like great detectives solve a mystery, <- Is the mystery the resolved path together, I'm guessing? 
but clues won't guarantee an afterlife. <- Lost me here. Clues - detective - mystery all flow together well, but maybe toying with different phrasings could jog new ideas, or possibly reordering the lines into couplets - the thought of dying first is killing me/like great detectives solve a mystery/we've searched and found our path, my wife/without guarantees of an afterlife - It still sounds like a forced rhyme but maybe what follows would reduce that impact by delving into it a little deeper. After all, this is the main sentiment you're expressing here.

Some nights I cage these fears inside my mind, <-Caging this fear in my mind at night
yet I am trapped by knowing people die <- I'm trapped by knowing that I could die
at any time, and leave their love behind, <- At any time leaving my love behind
while in the earth what's left of them must lie. <- Buried deep and out of sight?

So now the trail is lost or done; no light <- Now the trail is lost/done/ended, devoid of light
will end a tunnel, nor begin this trip. <- ? Not sure of the meaning here, so have no suggestion
I'll curse my daily nap, too old to fight, <- Like this, good line to show the aging process and why your mind is taking this turn
before the evening warms my lonely lip. <- Not sure of the meaning here, either. Why are you lonely if you're both still together?

And when I think I've overcome my fears, <- maybe drop the "and"
they'll make a grand escape; their tracks my tears. <- I would split this into two lines and use they instead of they'll. Is it "their tracks" as in the fears become the tracks of your tears? I like the idea of the transformation of fears into tears.

I feel these sentiments are the hardest to put into words and think that you've got a good start on doing just that. I've enjoyed hearing how that unfolds here and look forward to seeing what tweaks you use to refine it.