] My interpretation of the Allenham incident was that it seemed like such a get-the-family-acquainted-with-everything visit - showing your fiancee the house you'll share, which is a little insensitive to Mrs Smith since she's hardly dead yet! It also makes it socially inappropriate if Marianne and Willoughby are not engaged.

Although there are many things that are inappropriate about this visit to Allenham, including Willoughby and Marianne being out alone together, I think that a thought by Elinor goes to the heart of what is really wrong with it:

"Elinor could hardly believe this to be true, as it seemed very unlikely that Willoughby should propose, or Marianne consent, to enter the house while Mrs. Smith was in it, with whom Marianne had not the smallest acquaintance."

I think that shows why it is alright to tour a home when the owners are not there, but it seems to be a real social faux pas to go and look through someone's home if you have never been introduced to that person and they are there.