I think the fact that Lady Russell was quite well off, as well as 'older' (and I use that term loosely), may have had some thing to do with it. I have include a paragraph from Emma that expresses a similar thought as a further example. Public opinion may have frowned upon the remarriage of an 'older' (there's that word again), woman remarrying, because doing so would take an eligible man out of circulation and deprive the younger women who had not yet been married. Sorry if that's a little disjointed, I'm nearing the end of my shift. ;)

"That Lady Russell, of steady age and character, and extremely well provided for..." Ch. 1