First - whaaah really? I thought there was tons of post-marriage Darcy/Lizzy - was I wrong? and of course that pro-fic by (who is it by - where they solve murders?)

Second - yessss! A famous queer Austen critic, D.A. Miller, has written about this - I think one of his essays (possibly on Emma) is call "The Narrative of Perfect Happiness." As I remember, he argues that, in Austen's novel, Emma is promiscuous by proxy/in imagination, through her matchmaking and fantasies about Frank Churchill etc. But once she is married, she disappears: perfect happiness = "the end."