The happy couple...

 Marvin Gaye — It Takes Two  
Al Green — Let's Stay Together
The Long Ryders — Looking for Lewis and Clark
 Robert Palmer — Johnny and Mary
Pete Yorn & Scarlett Johansson — Relator
Dolly Parton & Kenny Rogers — Islands in the Stream
 U2 — Two hearts Beat As One
Ewan Robertson — Vincent Black Lightning
 Etta James — At Last
Sailor — A Glass of Champagne
 Bill Withers — Just the Two of Us
 Taylor Swift — Love Story
The Proclaimers — Let's Get Married
Fats Waller — Two Sleep People
Katy Perry — The One That Got Away
 The Pogues — A Rainy Night In Soho
Sharon Tandy — Two Can Make It Together
 Olivia Newton-John — We Go Together
Josh Ritter — Me and Jiggs
 The Moldy Peaches — Anyone Else But You
 Nina Simone — My Baby Just Cares for Me