Listed artist rather than song writer (may be same). Many are about lost love. It's a pretty eclectic list & it got a bit long (sorry - hard to stop once I got started. I really love these songs & many others). There are many more that could be included.

Just the Way You Are - Billy Joel
Songbird - Eva Cassidy (wonderful voice)
Feelings of Love - Patty Loveless
What's a Broken Heart - Patty Loveless
All the Love the World - The Corrs
One Night - The Corrs (More of a lust song really. Still Andrea Corr is really something)
How Sweet It is to Be Loved by You - Marvin Gaye
Crazy for You - Madonna
Careless Whispers - George Michael
Looking in the Eyes of Love - Patty Loveless
The Bluest Eyes in Texas - Restless Heart
I'll Be There - The Jackson 5 (as a child Michael Jackson had an incredible voice. The song is very uplifting)
Love Letters - Diana Krall
Faded Love - Patsy Cline
Love of My Life - Dave Matthews & Carlos Santana
Amy's Back in Austin - Little Texas
Star of County Down - Slainte
Faithfully - Journey
Baby I'm Yours - Barbara Lewis
(Our Love) Don't Throw it All Away - the Bee Gees
The Air That I Breathe - The Hollies
Have I Told You Lately That I Love You - Van Morrison (just an incredible performance)
Someday We'll Be Together - Diana Ross & the Supremes (blows me away every time I hear it. Fabulous early Motown)
The Girl form Ipanema -Astrud Gilberto & Stan Getz
Since I Fell for You - Bonnie Raitt
How Deep is Your Love - The Bee Gees
Take My Breath Away - Berlin
Don't Speak - No Doubt (written by a very hurt & pissed off (at the time) Gwen Stefani. This is an incredibly powerful song of love lost)
Here With Me - Dido
Show Me - The Pretenders (Chrissie Hynde's version of a love song)
Just a Little - The Beau Brummels
Can't Help Falling in Love - Elvis Presley (from the movie Blue Hawaii)
Lady in Red - Chris De Burgh
Stand By Your Man - Tammy Wynette (it somehow fits)