Sentence:  With this answer Elizabeth was forced to be content; but her own opinion continued the same, and she left him disappointed and sorry. It was not in her nature, however, to increase her vexations by dwelling on them. She was confident of having performed her duty, and to <WSD>fret</WSD> over unavoidable evils, or augment them by anxiety, was no part of her disposition. 
Meaning of the word marked with <WSD> tags:  To be anxious, to worry.