It felt very artificial to me. It's like the writers were looking for an additional gut punch and retconned one out of thin air. The brother being a psychopath is not a lot better. Still, I think the worst resolution was the absence of one for Lucy. She is one of the main characters and her resolution is as a secondary character that drops by in the resolution of the brother. They also manage to build her as a figure of modernity (part ways with the religious hypocrisy of her father, start a medical education) only to turn her into some sort of gold digger that fucks and blackmails her way into a marriage. Meh.
Still a great show.
I assume they are done? If that is the case, I would enjoy a spin-off about Cornelia making a fortune in Australia or about Algernon developing psychoanalysis.