It was not merely that Margaret was known to Mr. Thornton to have spoken falsely,--though she imagined that for this reason only was she so turned in his opinion,--but that this falsehood of hers bore a distinct reference in his mind to some other lover. He could not forget the fond and earnest look that had passed between her and some other man--the attitude of familiar confidence, if not of positive endearment. The thought of this perpetually stung him; it was a picture before his eyes, wherever he went and whatever he was doing. In addition to this (and he ground his teeth as he remembered it), was the hour, dusky twilight; the place, so far away from home, and comparatively unfrequented. His nobler self had said at first, that all this last might be accidental, innocent, justifiable; but once allow her right to love and be beloved (and had he any reason to deny her right?--had not her words been severely explicit when she cast his love away from her?), she might easily have been beguiled into a longer walk, on to a later hour than she had anticipated. But that falsehood! which showed a fatal consciousness of something wrong, and to be concealed, which was unlike her. He did her that justice, though all the time it would have been a relief to believe her utterly unworthy of his esteem. It was this that made the misery--that he passionately loved her, and thought her, even with all her faults, more lovely and more excellent than any other woman; yet he deemed her so attached to some other man, so led away by her affection for him, as to violate her truthful nature. 
It was not merely that Margaret was known to Mr. Thornton to have spoken falsely - though this was the only reason she imagined - but that her falsehood was linked in his mind to some other lover. He could not forget the fond and earnest look that had passed between her and the other man - the attitude of familiar confidence. The thought of this stung him.
In addition (and he ground his teeth as he remembered it) was the hour, dusky twilight; the place, so far away from home, and lonely. His nobler self had said at first that all this might be accidental and innocent; but once allow her the right to love and be beloved (and had he any reason to deny that right?) - she might easily have been beguiled into a longer walk, to a later hour than she had anticipated.
But that falsehood! which showed a fatal consciousness of something wrong, and to be concealed, which was unlike her. He did her that much justice, though it would have been a relief to believe her utterly unworthy of his esteem. It was this that made the misery - that he passionately loved her, and thought her, even with all her faults, more lovely and more excellent than any other woman; yet he believed her so attached to some other man that she would violate her truthful nature. 