You're so beautiful. It tore my heart to see you in despair like that...Please don't cry any more...I'd no idea you were so beautiful. I'd like to take you in my arms, and not let anything happen to you, ever...I've never seen anything in my life as beautiful as you are....

[getting up]

You must go now.

I'm not going. You know I'm not going. Oh, please let me stay.

But I want to be alone.

That isn't true. You don't want to be alone. You were in despair just now. I can't leave you now. You, you musn't cry any more. You must forget. Let me stay just for a little while. Ah, please let me stay.

For just a minute, then.
Bolded portion is ranked #30 in the American Film Institute's list of the top 100 movie quotations in American cinema.