Right Here by Staind is the most Zutara-fied song I've ever heard. I mean really, how could it not be?

... what do you mean, you don't see it? Here, let me tell you exactly why this song was made for Zutara:

Verse One

I know I've been mistaken
But just give me a break and see the changes that I've made
I've got some imperfections
But how can you collect them all and throw them in my face?

The first two lines, right off the bat, are perfectly describing Zuko's journey throughout the series and Katara's rejection of his change in episode 3.12, The Western Air Temple. "You can't possibly think that any of us could trust you, can you?" or that infamous line "You might have everyone else buying your 'transformation', but you and I both know you've struggled with doing the right thing in the past."

For the next two lines, we've got to jump forward to episode 3.16, The Southern Raiders. "Maybe you could re-conquer Ba Sing Se in the name of the Earth King. Or, I know. You could bring my mother back." And speaking of Ba Sing Se, who could forget the crystal catacombs? "You’re a terrible person, you know that‌? Always following us, hunting the Avatar, trying to capture the world’s last hope for peace! But what do you care?‌ You’re the Fire Lord’s son. Spreading war and violence and hatred is in your blood."

Chorus

But you always find a way to keep me right here waiting
You always find the words to say to keep me right here waiting
And if you chose to walk away I'd still be right here waiting
Searching for the things to say to keep you right here waiting

Katara: It’s just that for so long now, whenever I would imagine the face of the enemy, it was your face.
Zuko: My face. I see.
Katara: No, no, that’s not what I meant.
Zuko: It’s ok. I used to think this scar marked me. The mark of the banished prince, cursed to chase the Avatar forever. But lately, I’ve realized I’m free to determine my own destiny, even if I’ll never be free of my mark.
Katara: Maybe you could be free of it.

I just went there. Oh yeah.

Verse Two

I hope you're not intending
To be so condescending it's as much as I can take
and you're so independent
you just refuse to bend so I keep bending till I break

Every Zutara shipper can attest to the fact that Katara isn't exactly the nicest person when it comes to Zuko. For example, in episode 3.13 (The Firebending Masters) she says "I'm just laughing at the irony. You know… how it would have been nice for us if you lost your firebending a long time ago‌" and "Maybe you're just not as good as you think you are." She's cold and cruel; so very condescending to Zuko.

Independent. Even the Kataang shippers have this one downpat, amirite? Like in episode 1.06, Imprisoned, she says plenty of good, strong, independent things. "I'm not leaving. I'm not giving up on these people... The time to fight back is now... etc." Also, there's this from episode 3.16:
Zuko: You should get some rest. We’ll be there in a few hours. You’ll need all your strength.
Katara: Now, don’t you worry about my strength. I have plenty.

Getting back to the song ties and Zutara, we have to go back to episode 3.16, where there's a particular scene or two I'd like to share.
Katara: What are you doing‌!?
Zuko: Keeping rocks from crushing you.
Katara: Okay, I’m not crushed. You can get off me now.

Repeat Chorus

Bridge

I've made a commitment
I'm willing to bleed for you
I needed fulfillment
I found what I need in you

Four words: Sozin's Comet Agni Kai. Seriously.

Not enough to convince you? Fine, take a look at this:
The frame rate slows to a crawl as the lightning shoots from Azula’s finger. Close up of Zuko. An expression of shock spreads over his face as he turns to his right. Zuko’s legs as he runs to the right, trying to get in between Katara and the lightning as it shoots from Azula in the background. Close up of Katara’s face and zoom in on her eyes as they reflect the approaching lightning. Go to the view from in front of Katara as Zuko leaps between her and the lightning.

Bridge cont.

Why can't you just forgive me?
I don't want to relive all the mistakes I've made along the way
But I always find a way to keep you right here waiting
I always find the words to say to keep you right here waiting

I think that's all Zuko was ever looking for from everyone. Forgiveness. If you really stop to consider how many mistakes he's made, and how painful some of those must be, comments like "Maybe you could re-conquer Ba Sing Se in the name of the Earth King" and "You can't possibly think that any of us could trust you, can you?" must truly hurt, right?
Yet somehow, in some way, the two manage to find each other again and again.

Final Chorus

But you always find a way
To keep me right here waiting
You always find the words to say to keep me right here waiting
And if I chose to walk away would you be right here waiting?
Searching for the things to say to keep me right here waiting

This is perfect for the conclusion of the series. Are they really willing to let each other go? If this is from Zuko's point of view, he's wondering if she cares enough to stop him from going.

But does she...?