Mrs. Dashwood feels sorry for Willoughby after Elinor tells her the story (at Marianne’s request). However, the suffering he caused and his stained reputation cannot be undone. Colonel Brandon is Mrs. Dashwood’s new favorite.
Marianne realizes she could have never been happy with Willoughby. She would have eventually learned the truth about his character and lost respect for him. She can’t love what she doesn’t respect. Elinor also points out that he was without restraint and extravagant, and they would have been very poor. He would have resented Marianne’s efforts to be frugal. Willoughby’s repentance is still laced with selfishness. He would have not been happy with Marianne if he had married her.
Elinor hears that Mr. Ferrars has married from their manservant, who encountered Lucy.
Mrs. Dashwood realizes that Elinor, though more restrained in her emotions, suffered from her disappointments just as much.