Some good songs here...
Every romantic song list should have a little Marvin Gaye in it. Specifically...Let's get it on
I'd also add...
Banana Pancakes
Better Together - both by Jack Johnson (I mentioned this in another thread, but I'm kind of on a Jack Johnson kick lately...)
Your body is a wonderland - John Mayer
All for you - Sister Hazel
Kiss me - Sixpence none the Richer
The obligatory mention...Crash - Dave Matthews
Signed Sealed Delivered - Stevie Wonder
Angel of Harlem - U2
Crazy Love - Van Morrison
You and Me - Lifehouse
Julia - The Beatles
I could go on and on and on....