One day, she decided to ask him.

The next, she shrank in burning confusion, for when Jimmy Malone had asked for her love, she had admitted to him that she loved Dannie, and Jimmy had told her that it was no use, Dannie did not care for girls, and that he had said he wished she would not thrust herself upon him.

On the strength of that statement Mary married Jimmy inside five weeks, and spent years in bitter repentance.
That was the thing which held her now.

If Dannie knew what she did, and did not care to marry her, how could she mention it?
Mary began to grow pale, and lose sleep, and Dannie said the heat of the summer had tired her, and suggested that she go to Mrs.Dolan's for a weeks rest.

The fact that he was willing, and possibly anxious to send her away for a whole week, angered Mary.