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.
Austen chose Easter for the most significant turn in Pride and Prejudice.
When talking of love it is important to define the word. Is it emotion, feeling, decision or all of the elements? According to some Christians i.e. Anglicans and Catholics four kinds of love must be present for the Holy Matrimony to be valid and complete. I’ll try to explain, on their example, Elizabeth’s growing love for Darcy in Pride and Prejudice.
There is a lot of confusion as to when and why Elizabeth Bennet fell in love. 
Mending My Own Pen 