What is the intention of Colonel Brandon in telling the story of Eliza and Willoughby to Elinor? What is Elinors opinion of the Colonel for sharing the news?

I think it helps to make Marianne feel better for not ending up married to Willoughby, the guy turns out to be all flash and no substance! I think Elinor has a new respect for the Col. Perhaps he might be good for her sister (Marianne) after all.