Oh, choices, choices!
Well, I have 2; because I just can't pick one, obviously ;)
The first is "Love is not a Fight" by Warren Barfield. And yes, it is the song played in Fireproof when they get their vows renewed! Aww! (And I'm not sure why the video turned out to be so big. Whoops! :P)
And then the second is Brandon Heath's "Love Never Fails". So, so beautiful. And I think that I either read or saw somewhere that he sang it at Carrie Underwood's wedding! That's just snazzy.