No just Cause or Impediment why these Two Persons should not be joined together
Dorrit accepts the engagement with his usual pompousness. Mostly for him it's a way to secure the family further in society, so it's all to the good.
Mrs. Merdle also likes the match.
Dorrit and Merdle write a few letters back and forth to settle money questions, and then it's off to the races. Or, you know, to the wedding.
Dorrit then wants to announce the engagement to Mrs. General. Fanny has no desire to give her any such preferential treatment, but Dorrit commands it.
There is a totally hilarious exchange where Mrs. General says that she highly approves, and Fanny is all, "oh, well, thank goodness, how could I possibly go through life without your approval?" for two paragraphs. Awesome. Fanny's a firecracker.
After telling her off, Fanny runs to Amy to complain about Dorrit and his special treatment of Mrs. General.
Now Fanny is the queen bee and the belle of the ball in society, and everyone treats her with even more respect and grudging admiration.
Finally the vacation season is over and Sparkler has to go back to England to start his job.
Fanny has another confab with Amy where she tells her that she needs to marry Sparkler immediately and go to England with him because he's too much of an imbecile to be trusted alone.
Fanny also asks Amy to vigorously protest if Dorrit decides to propose to Mrs. General.
Amy doesn't make any such promise and is just mostly sad that she won't get to go to England too.
So – wedding planning and preparations.
And then the big day. It's as fancy and elite as anyone could want. It goes off without a hitch, and it's totally bride-centric.
Afterwards, as Fanny and Sparkler drive off in their carriage, the narrator says that "after rolling for a few minutes smoothly over a fair pavement, [they] had begun to jolt through a Slough of Despond, and through a long, long avenue of wrack and ruin" (2.15.90). Oh, snap! That's telling them.
That night Dorrit tells Amy that he's super happy about Fanny. Oh, and that all of this should be a lesson to Amy, who also will hopefully be married off soon.
Amy flips out in fear and sadness and says she just wants to stay with Dorrit.
But he is all faux-generosity and replies that he couldn't possibly ask for such a sacrifice from her. Oh, right, dude, and what do you call her whole life so far?
Amy tries not to think about the idea that he's trying to get her out of the way so he can marry Mrs. General.