Twenty-four hours ago, he thought that he would be rich and able to pay back Mr. Garth and marry Mary Garth without having to work for it.
His father now wants him to commit to becoming a clergyman, but Fred still doesn't think he's cut out for it.
Mr. Vincy is grumpy enough about Fred that he says he wants to Rosamond to put off her engagement to Lydgate until Lydgate has a better income.
But Rosamond knows how to manage her father.
She has a stubborn streak, and he knows it.
Mrs. Bulstrode doesn't like the engagement, either – she's worried that her niece Rosamond won't be able to live happily without a huge house, fancy furniture, and expensive clothes. And she's probably right.
Lydgate himself thinks that it's perfectly natural to rent a nice house and buy "good" (i.e., expensive) furniture.
He's not trying to be extravagant, but he just doesn't know any other way to live.
When Lydgate learns that Mr. Vincy was encouraging Rosamond to break up with him, he persuades her to get married even sooner.
She asks him to write to her father, and then Rosamond tells her father in person, herself.
Her father's stubbornness is nothing to hers, and so he agrees to a quick marriage.
Meanwhile, Rosamond still wants to meet Mr. Lydgate's fancy aristocratic relatives.
She beats around the bush a little, and finally charms him into agreeing to swing by the family estate to meet his uncle and cousins on their way back from their honeymoon.