The Palmers were to remove to Cleveland about the end of March, for the Easter holidays; and Mrs. Jennings, with both her friends, received a very warm invitation from Charlotte to go with them. This would not, in itself, have been sufficient for the delicacy of Miss Dashwood; -- but it was inforced with so much real politeness by Mr. Palmer himself, as, joined to the very great amendment of his manners towards them since her sister had been known to be unhappy, induced her to accept it with pleasure. (Ch. 39)

All who were friends of Marianne, Mrs. Jennings, the Palmers and Sir John gave Willoughby up as an acquaintance except for the cold-hearted Lady Middleton. In Ch. 41 Willoughby says Sir John had cut him since his marriage and only spoke to him in Drury-lane lobby out of indignation and concern for Marianne—it does sound like Sir John. As above, I think the amendment of his manners towards Elinor and Marianne show Mr. Palmer does not approve of Willoughby’s behavior and it appears he did not approve of him before either. Mr. Palmer never visited Willoughby or invited him to Cleveland when canvassing against the election because he is in the opposition (Ch. 20). So why would Mr. Palmer admit Willoughby into his home to pester Elinor now? (:D)