The Marquis de La Mole finally caves and gives Julien some of his property in the town of Languedoc for his future income. After that, the marquis doesn't want to have any more relationship with Julien or his daughter.
Mathilde writes back and begs her father to attend the marriage ceremony. The marquis' first thought is to give Julien a ton of money to leave Europe forever and write a note to Mathilde saying he was going to kill himself. In the end, he decides not to.
The main question that the marquis worries about is whether Julien began his relationship with Mathilde with the intent of scamming money.
In the end, the marquis gets Julien a high posting in the army, which basically makes him a respectable dude in French society.
This is really the final thing Julien needs to rise out of his lower class status. He even takes on the new name of Julien de La Vernaye.
Everything finally looks like it's all wrapped up nicely.