Sam: Hey, wait, listen to me. I did not save your letters.
Diane: Where did this come from?
Sam: I found it in my apartment. I got pizza boxes that old that have more meaning. Come on.
Diane: Sam Malone, look me in the eyes and tell me you don't love me. If you can do that, then I have no choice but to believe you.
Sam: Oh, boy, I'm sorry, but... I don't love you, Diane. Uh, I thought I did once, but I was wrong. There's nothin' goin' on between us here. I mean, it's all over.
Diane: Very well. That was in the eyes, wasn't it? I guess I'll go before I make a bigger fool of myself.
[After Diane leaves, Sam takes the letter and goes to put it in a carefully-tied pile of letters he keeps in a box inside his filing cabinet.]
Diane: Aha!
Sam: What the hell are you doing?
Diane: I came to catch you in a lie, and I did. Don't I know my darling better than anyone else?