During Jane Austen’s time, women were not as independent and free as they are now. Very few women received formal education. Besides, there were not many respectable jobs for women, which meant financial insecurity and dependency. The only way women could gain social mobility was to marry rich men. Hence, finding the right partner for marriage was a serious business for women. Women were supposed to learn dancing, singing, sewing, etc. to impress men. Very few marriages were born out of love.
In Pride and Prejudice, Charlotte Lucas and Mr. Collins' marriage is an example of this trend. In Charlotte’s view, the purpose of marriage is just to get a good home.
"I am not a romantic. I ask only a comfortable home..."(Charlotte Lucas to Elizabeth)
Mr. Collins, as we know, wanted to marry Elizabeth first. However, Elizabeth doesn’t have this view of marriage, and hence she rejects Mr. Collins' proposal. She doesn’t fall for Darcy because he is very rich. She starts loving him when she realizes that she had been wrong in understanding him. Marriage between Jane and Bingley also occurs because of mutual love and attraction.
It is important to know that women didn’t have any right over ancestral property and whatever they had would become their husband’s possession after marriage. And so, women were in danger of falling for poor men, who wanted just their money. We see Wickham marries Lydia to make some money.