So if I didn't make an AMV to this song I think I might have died. It's a few years old, but it's still my all-time favorite romantic song, and I think the lyrics REALLY match Lelouch and Suzaku well. Here are the (roughly translated) lyrics:

Ill take a picture of you.
I will remember anyway and I know you dont want me to.
I will call you because you wont answer.
It makes me laugh now, thinking of you like you were a game
And realizing that Ive lost you, Ill take another picture of you.

Because you are so little and you could slip from my hands.
And the days that were already far away will turn into years.

[CHORUS]
And youll forget me.
When it rains, the skyline and the houses make me remember you
And it will be so beautiful
Because happiness and pain have the same taste with you.
I would just like for the night to go away fast,
and suddenly everything you have from me not to come back.
And I want love and all the attention you know how to give.
And I want indifference if youll ever want to hurt me.

And Ive recognized you in a strangers look.
But even if you were here Id feel you distant.
What could this small feeling mean,
When you are my greatest dream, my worst nightmare.

We are sons of different worlds, but we have a single memory
that erases and draws the same story.

[CHORUS]

The memory is not enough anymore.
Now I want you to come back.
And it will be so beautiful
Because happiness and pain have the same taste,
The same taste as yours.
I would just like for the night to pass fast,
And suddenly everything you have from me not to come back.
And I want love and all the attentions you know how to give.
And I want indifference if youll ever want to hurt me.
And I want indifference if youll ever want to hurt me.

Song: 'Ti Scattero Una Foto' by Tiziano Ferro
Anime: 'Code Geass: Lelouch of the Rebellion' by Taniguchi/Okouchi/Sunrise/etc.

AMV by B of TeamJAMB! (less info)