Even in Gwendolen's mind that result was one of two likelihoods that presented themselves alternately, one of two decisions toward which she was being precipitated, as if they were two sides of a boundary-line, and she did not know on which she should fall. 
Gwendolen felt herself being hurried towards two alternative likelihoods; two decisions, like two sides of a boundary-line, and she did not know on which side she should fall. 