He was conscious all the while that there was a something wrong in his argument,--that Paul when he commenced to love the girl knew nothing of his friend's love,--that the girl, though Paul had never come in the way, might probably have been as obdurate as she was now to his entreaties. 
He was conscious that there was something wrong in his argument; that Paul when he began to love the girl knew nothing of Roger's love - that the girl would probably have refused him even without Paul. 