The more she thought of it, the more she wondered what the question was, that he did not dare to ask; and whether it was of herself or himself that he would ask it--if he did dare.

Then, with benumbing force, one day, a possible solution of the mystery came to her, he had found out that it was true (what all his friends had declared of him)--he did not really love any girl, except to paint! The minute this thought came to her, Billy thrust it indignantly away.
It was disloyal to Bertram and unworthy of herself, even to think such a thing.

She told herself then that it was only the portrait of Miss Winthrop that was troubling him.

She knew that he was worried over that.
He had confessed to her that actually sometimes he was beginning to fear his hand had lost its cunning.

As if that were not enough to bring the gloom to any man's face--to any artist's! No sooner, however, had Billy arrived at this point in her mental argument, than a new element entered--her old lurking jealousy, of which she was heartily ashamed, but which she had never yet been able quite to subdue; her jealousy of the beautiful girl with the beautiful name (not Billy), whose portrait had needed so much time and so many sittings to finish.