"I suppose you're writing to your mother." "Why do you think so ?" he asked curiously.
"You write to her every day, don't you ?" "Yes," he said, "but how do you know ?" She looked at him with unblushing deliberation.

"You wrote every day.

...
If it was to a woman, I wanted to know.

...

And I told Grace Ferrall that it worried me.