The Gravity of a Long Distance Relationship

This is a song, I think, written to a former lover, a former someone that he, it's sung by a man and a woman. When is the last time you heard a love song being sung to an ex-partner? There's nothing like it. It's amazing. If you're ever in trouble, I'll be there on double. Anyway, this song ain't not mountain high enough. But if you need me, call me no matter where you are."