Why does Charlotte Lucas get married?

Charlotte Lucas marries Mr. Collins primarily for security and stability rather than love. At a time when women had limited options for independence, marrying a man with a steady income offered her financial security and social standing. She understands that her chances of marriage are slim as she ages, so she pragmatically accepts Mr. Collins's proposal despite his shortcomings. Her decision reflects the societal pressures and constraints faced by women in her era.