The song is "It's Not Suppost to Go Like That" by Rascal Flatts.
The part written in the song reminded me of Faith. Who is Harvestmoonluvr's character from her manga Faithfulness. (it's amazing you should read it) The whole song reminded me of the story so far, but that one part matched Faith perfectly.
First thing my mom pointed out was, "Suppost isn't a real word...." Me: "I kno... It's part of the song...."
Song:
Tommy found his daddy's gun
And Joey had never seen one
Real cowboy all dressed up
As he held it in his hand
Said, "You be good and I'll be bad"
Then he pulled the trigger back
Stopped little Tommy in his tracks
And said, "Get up, man"
People came from miles to say goodbye
To the Wilson's youngest son
His innocent life had just begun

CHORUS

It's not suppost to go like that
It's not intended to end that way
Life is a journey constantly turning
Down an unknown path
But it's not supposed to go like that

Jimmy had his daddy's car
And the keys to Jenny's heart
A fifth of whiskey on the floorboard
Almost gone
Havin' the time of their life
Had only one thing on their mind
Never saw the flashin' lights
Or the train comin' on
Now there's a wreath and two small crosses
On the right side of the road
Reminders of a love that won't grow

REPEAT CHORUS

I wonder if guardian angels cry
When they see it all played out
And as they stand with their hands tied
Oh, do they cry out loud

It's not suppost to go like that
No, it's not suppost to go like that
No, it's not suppost to go like that
No, it's not suppost to go like that
No, it's not suppost, it's not supposed to go like that
No, no, no, it's not suppost to go like that

~Chero~