She knew he admired her one talent, respected her independence, and enjoyed her society; but when something warmer and more flattering than admiration, respect, or pleasure crept into his manner, she could not help seeing that one of the good gifts of this life was daily coming more and more within her reach, and began to ask herself if she could honestly receive the gift, and reward the giver.
At first she tried to think she could, but unfortunately hearts are so "contrary" that they won't be obedient to reason, will, or even gratitude.

Polly felt a very cordial friendship for Mr.Sydney, but not one particle of the love which is the only coin in which love can be truly paid.

Then she took a fancy into her head that she ought to accept this piece of good fortune for the sake of the family, and forget herself.

But this false idea of self-sacrifice did not satisfy, for she was not a fashionable girl trained to believe that her first duty was to make "a good match" and never mind the consequences, though they rendered her miserable for life.

Polly's creed was very simple: "If I don't love him, I ought not to marry him, especially when I do love somebody else, though everything is against me." If she had read as many French novels as some young ladies, she might have considered it interesting to marry under the circumstances and suffer a secret anguish to make her a romantic victim.