[quote=Nephriel]
Actually, in my playthrough killing Flemmeth didn't happen till quite some time after Lothering was destroyed. I guess they figured most people wouldn't have already gotten Morrigan to trust them enough to ask them to kill her that early. Honestly, she never asked me till I had her approval almost maxed out. I was already in Orzammar.
[/quote]

Most people, if not everyone doesn't kill Flemeth right after Lothering.

At least not without cheat codes, and that shouldn't count for canon story timelines or anything.