For Jane Austen love was absolutely necessary for a good marriage. However, in English society at the time, which is depicted in the novel, love is not the greatest consideration for marriage. The ideal goal for marriage is to marry someone financially capable of supporting you. Love is secondary. Austen mocks this practice in the book.
For example, Mrs. Bennett is constantly reminding her daughters about the rule that since there is no male heir among her children, that their home will pass out of their family to the next male in the family, Mr. Collins. The Bennetts will be homeless when Mr. Bennett dies. So it is imperative that the girls, especially Jane and Lizzy, find husbands who can provide them with a home and possibly their mother and sisters as well.
Marriage is considered an arrangement between parties who occupy the same social level. Love is certainly a necessary consideration, but not required for a good match. For example, Darcy has been promised to Lady Catherine Debourgh's daughter since birth.
Even though he does not love her, he is supposed to marry her. Darcy is an exception, since he does fall in love with Lizzy, but is reluctant, at first to court her because he believes that her family is socially inferior. Darcy and Lizzy's marriage is an example of both love and financial security coming together. She and Jane both marry men who not only love them but can support them well.
'Romantic love' is the central theme which unites all the incidents and the characters in "Pride and Prejudice." But there is nothing 'romantic' about Jane Austen's treatment of 'romantic love' in the novel. 'Romantic love' is checked and controlled by the incomes and financial freedom of the partners involved. In this manner Jane Austen is able to blend 'romance' and 'realism.' For example, Lydia and Wickham who elope 'romantically' have to be rescued by the generosity of Darcy before they are married.
The restraining power of money on 'romantic love' is spelt out in the thematic statement found in Ch.27, "Where does discretion end, and avarice begin?", when Elizabeth replies to her anunt's query concerning Miss King the latest lover of Wickham. Her aunt is relieved to know that Elizabeth is not in love with Wickham who has virtually no income at all and is only employed temporarily in the Militia.
Another important consideration in love and marriage was the social class to which the characters belonged:
At that time, ownership of land and not money was the single most important criterion which determined the social status of an individual. Lady Catherine tries unsuccessfully to dissuade Elizabeth from marrying Darcy,because she is poorer than him but Elizabeth angrily retorts: "In marrying your nephew, I should not consider myself as quitting that sphere. He is a gentleman; I am a gentleman's daughter: so far we are equal."(Ch.56).