Quote 1
"There certainly are circumstances," said Willoughby, "which might greatly endear it to me; but this place will always have one claim on my affection, which no other can possibly share." (14.7)
In this declaration, Willoughby asserts the fact that Barton Cottage, for all its flaws, is more homelike to him than his own houses at Allenham and Combe Magna because of one thing – presumably Marianne. Is it love, then, that makes a house a home?
Quote 2
To avoid a comparative poverty, which her affection and her society would have deprived of all its horrors, I have, by raising myself to affluence, lost everything that could make it a blessing. (44.13)
Willoughby confesses that he realizes the error of his way – he's basically sold his soul for Miss Grey's fortune, and now can never be happy.