After visting Remberley, Elizabeth had respect, esteem and gratitude for Mr Darcy. WHy did Elizabeth feel grateful?

From the text:

But above all, above respect and esteem, there was a motive within her nof goodwill which could not be overlooked. It was gratitude; gratitude, not merely for having once loved her, but for loving her still well enough to forgive all the petulance and acrimony of her manner in rejecting him, and all the unjust accusations accompanying her rejection.