This is an interesting poem. It reminds me of a good old Nick Cave and the Bad Seeds "Murder Ballad". I do like how you transition fairly smoothly from:

"I was your shadow on sunny days, your stray moonbeam at night"

And within the next stanza:

"I used to think you were beautiful beyond compare,
And I couldn't help myself (insert a comma here please)I would just stare and stare.
You used to drive away from me, and leave me cold,
Standing (insert word "there") alone on your corner on rainy days."

the whole thing became very easy to relate to (which by the next stanza, it makes a person feel cold because you wrapped them into the story so nicely).

The third stanza is when we start to see the beginning to the end, though I didn't even foresee how far this character would go.

The fourth and fifth stanzas twist the story as the character's mind must twist. I love the last few lines, excellent!

The whole poem to me flowed nicely, it told a horrifying story, where in the beginning the reader is sucked in, and by the end they are wishing they hadn't been, again excellent! I have faved his wonderful poem!