Does Jane Austen address the theme of gender injustice in her treatment of love and marriage in "Pride & Prejudice"?
The best example of gender injustice comes through the example of the charming bad boy Mr. Wickham. Here is a man who has repeatedly done foolish, unwise things and yet enjoys a solid reputation in society, and could still have his pick of young ladies to marry if he so desired. Even after he absconds with the foolish Lydia, his reputation remains relatively unscathed, while Lydia becomes a marked, fallen, disreputable woman. If Wickham were to walk away from the Lydia situation without marrying her, he could probably have gone on to lead a life unmarked by his actions, and continue on to find another girl of some means to marry. Lydia on the other hand, if she hadn't married, would have been ruined. It would have been the end of her chances in society, of ever finding a suitable match, or being considered worthy of any sort of social standing.
This demonstrates the great injustices that were found in Austen's time, in regards to gender. Women were held responsible for any bad behavior, while men could do pretty much as they pleased. Women also became a "burden" on their parents if they didn't get married (hence Charlotte's marriage to Mr. Collins to get out of her parent's house), and were held accountable for their family's foibles and faults (Mr. Darcy convincing Bingham, in part, to walk away from Jane because of her silly family). Overall, women really got the short end of the stick when it came to freedom to pursue love and marriage separate from reputation, money, burden of family and societal norms.
I hope that those thoughts helped a bit; good luck!