Because I couldn't remember.
JOY
It wasn't your fault.
TYLTYL
I know, but I hated it.... And you were so pale, so dreadfully pale; and you never spoke.... How long had you loved me?
JOY
Ever since I first saw you, when you gave me the Blue Bird.
TYLTYL
So have I, so have I, but I had forgotten.... Never mind: we're going to be tremendously happy, for they've settled it, you see; they want it.
JOY