...perhaps I should clarify, I was trying to pinpoint when I as a reader was alerted to being worried about the relationship specifically with Willoughby. Although the narrator hints at the plot taking some twists, do we know here that this has to do with him? They could have gotten married and then the troubles begin, etc. I guess, I was going on my own sense of being totally ignorant of the story before now (no spoiling to myself) to determine when my ears perked up regarding Willoughby in particular. Barbara makes a good point about back in Chapter 13 and the impropriety of going around unchaperoned at Allenham, but even there, you could see that Marianne did not feel alarm there - no impression was given that she was taken advantage of there. And I suppose even until the day Willoughby left, Marianne didn't give the impression of being taken advantage of. Perhaps Ch 13 was a better place to start being a bit concerned. But the fact that it was Mrs. Jennings, and even Marianne's argument to that effect carried a bit of weight with me - Mrs. Jennings I could not tell whether she was scolding or rather just trying to embarrass Marianne and Willoughby (not unlike the way she wanted to out Elinor about her beau "Mr. F" - the fact that Elinor might have one was not improper - it was really embarrassment that Mrs. Jennings (in good fun) was aiming at. It wasn't until Elinor's concern was peaked that I as a reader felt my concern as well. I suppose it does depend on the reader...