...about an attachment to Darcy would have been unforgivable prying into Lizzy's private affairs. If Mrs. Dashwood would not ask her own daughter Marianne in S&S whether an engagement existed, for an aunt to do so would be even less proper. (Sorry for the reference outside P&P.) We know Aunt Gardiner is very discrete; JA lets us know how much she would like to ask (and at times how much Lizzy wishes she would say something), but such sharing of Aunt Gardiner's suspicions does not occur until her letter about the Lydia/Darcy connection in Chapter 52. At that point it is in response to an inquiry from Lizzy, which apparently opens a door ever so slightly on the topic.