He decides that she is a little crazy.

STEVE, soothingly, 'Come now, we won't go into that again. It was just
a mistake; and now that it is all settled and done with, I'll tell you
what we shall do. You will let me get you a cab--' She shakes her
head. 'I promise not to listen to the address; and after you have had
a good night you--you will see things differently.'

AMY, ashamed of her momentary weakness, and deciding not to enter it
in the diary, 'You are very clever, Mr. Stephen Rollo, but I don't
leave this house without the letters.'

STEVE, groaning, 'Are they your letters?'

AMY. 'How dare you! They are the letters written to you, as you well
know, by--'

STEVE, eagerly, 'Yes?'

AMY. '--by a certain lady. Spare me the pain, if you are a gentleman,
of having to mention her name.'

STEVE, sulkily, 'Oh, all right.'

AMY. 'She is to pass out of your life to-night. To-morrow you go
abroad for a long time.'

STEVE, with excusable warmth, 'Oh, do I! Where am I going?'