"Why are you crying ?" "I'm not!" she declared vehemently.

"I wasn't! You--you startled me--that's all." She turned her back on him and hastily dabbed her eyes.

She was furious with him for coming upon her thus.
He stood at the window, looking out upon the long, black barges in silence.
After a few seconds of desperate effort she controlled herself and turned round.
"I never heard you come in.

I--must have been asleep." He did not look at her, or attempt to refute the statement.
"I thought you were going to be out this afternoon," he said.
"So I was.

So I have been.