There's some Allison Moorer that would fit the bill, maybe "Send Down An Angel". Her duet with Kid Rock, "Picture", definitely works. (I much prefer it to the Sheryl Crow version.)
You have Carly Simon's "Jesse", which reminds me that Joshua Kadison's "Jessie" would also work.
The first song that comes to mind:
You Just Keep Me Hanging On - Supremes
I don't really know Allison Moorer--I will have to give her a listen!
ETA: DUH! I don't know how I missed that one, Hec. Thanks!
I can't let go - The Hollies [link]
Maybe Art Garfunkel's "All I Know".
If you want anything from Country Music ("The Music of Pain." - Xander Harris)
She Thinks That I Still Care - George Jones
Walking After Midnight - Patsy Cline
Til I Can Make It On My Own - Tammy Wynette (her late masterpiece)
Gravity, Sara Bareilles. Still can't listen to that one due to personal associations with trying and failng to break up with KBD.
Since not being able to stay away from people is kind of my romantic life in a phrase, and I've been making a soundtrack for myself since first grade... I'm sure I'll have a lot more once I check my iTunes.
Cory Branan, Troublesome Girl
Joan Jett, I Hate Myself For Loving You
Adele must have a song or five that would fit.
Gravity is totally needed on the Blade soundtrack!
I have the Joan Jett too, so it is added.
I think Adele's whole "21" CD fits.
You don't have any Kelly Clarkson on there.
What about "Every Breath You Take"