At the beginning of the 18th century arranged marriages were the norm, but by the end of it they fell out of favour with nearly everyone, the upper class excepted. Family’s interest stood in opposition to Christian morality. Marriage should be for love, because it’s instituted by God, and not by any civil contract. Anglican marriage is a lesser sacrament, and its only condition is the mutual vow of love. One can lie and sign any papers, but one cannot possibly cheat God or hope that God would bless what is an abuse of the sacrament He instituted.
In fact the romantic notion of love and marriage revived because people became more concerned with religion than they were in the 17th century. Yet, it doesn’t mean that they ceased to care about the prudential aspect of it. Parents took care that their daughters met only those gentlemen they could marry without degradation. In other words they were free to fall in love with the men they knew, but the group of the men they were allowed to meet was limited in advance.
In Rambler 97 Samuel Richardson argues in favour of the course of courtship of his own youth. It is interesting to see how much the mores had changed between his times and those of Austen.
Austen famously paraphrased his words in Northanger Abbey:
for if it be true, as a celebrated writer has maintained, that no young lady can be justified in falling in love before the gentleman’s love is declared, it must be very improper that a young lady should dream of a gentleman before the gentleman is first known to have dreamt of her.
It is likewise significant to note that no positive hero of Austen’s ever seeks the lady’s family’s approval for courtship or asks for her hand before her own consent is given. Such a kind of behaviour is left to men like Mr. Collins or Henry Crawford.