The societal status of women in this period is crucial to fully understanding Juliet's character. Women were not allowed to own property or establish monetary claims in their own names. (Remember that women were not even allowed to act in Shakespeare's time, so even Juliet's role was played by young boys.) Passed from their fathers (or oldest brother in his absence) to a husband, women of noble ranks often had no determination in whom they would marry and were often used as financial or political pawns.
Juliet is expected to marry Paris. This has been decided by her father and is a decision Paris is in agreement with. To disobey the authoritative men in her life is no small decision--particularly for a young girl of 13. (Although it was common for girls to be married fairly young, this is an exceptionally young age.) Juliet's character is often dismissed as a flighty young girl almost mindlessly following the "fate" of the stars, but her willingness to circumvent societal expectations and marry a man whom her father did not support shows both her courage and her willingness to risk everything for Romeo. Thus, this context highlights the certainty she must have felt in their relationship.
Also of cultural significance is that the play was written somewhere around 1595 and during the reign of Queen Elizabeth I. The arts flourished during this time period, and Shakespeare was invited to her court more than once. Queen Elizabeth I was required to be a courageous and tenacious ruler; she remained on the throne for more than 40 years, one of the longest reigns in England's history.
Perhaps there is a bit of this independent spirit, standing tall in her own right instead of aligning to the wishes of the men in her life, in Juliet. Although the "Virgin Queen" chose to be married only to her country (while Juliet chooses marry and spend a honeymoon night with a man she has only known for about 24 hours), they both show an independence in making their own sexual decisions, regardless of how they are judged by societal standards.