-since day one

[Todd]

Okay some comments on the edit.

First Edit

I added a little more story... Thanks for bearing with my heartbreak - I'm concerned it's a little cliche.

Since Day One

It started with you,
This year...
Guiding me through the crowds of people,
Your hand on my back.--This is starting to get there. Again I can't tell if this is patronizing or helpful on the other person's part. I default to patronizing but its still a bit too vague of a detail. I read another poem once that said I fold your underwear wrong, wrong, wrong...not suggesting it just saying I think you need to commit stronger to raise the stakes.

This year,
Won't end with you.--when you really think about it the earlier this year to set this set of lines up. All of it actually doesn't add a whole lot. We have to read in the tone and it could be very off. It could be snarky or it could be cancer (for instance) no way of knowing. All we're told is that it will end without this person. There is no emotional investment from us to make it carry any weight.

Your hand on my back.
Guiding me,--again the repetition is a repetition of a vague experience. It doesn't have the effect you intend unless we guess right.
"I will not give up on you."--Now the speaker, the I isn't giving up on the other person. Again a bit vague. Dialogue is often a bad tool in poetry. It can work but it can also function as emotional shorthand without earning the moment. I am not suggesting it can never be used.
As I slowly lit the fuse 
To ignite my heart.

I ended you,
And me, --These four lines are better especially since the fuse was lit surprisingly to ignite the speaker's heart and not blow up everything.

Us. 
Like the fireworks,
Just a temporary show.
Red and green and gold...
And then only blackness.

We've been sitting on dynamite. --I hesitate to give line notes as I don't want to warp what your doing. But the ignite my heart bit is the one interesting part you've got going in my opinion. Maybe the speaker didn't understand they were lighting a fuse or maybe they thought they would get fireworks and only realized too late that they got dynamite. If so, knowing that how can you build the poem with the end in mind?

Just some thoughts.

Best,

Todd