In the context of 16th century court life under the rule of Henry II of France, political agendas, machinations, and the pursuit of prohibited desires guided the behavior and actions of the nobility. One of the primary ways for a woman to gain upward social mobility or maintain an already elevated social standing was to marry well, so love was often a practical, not a romantic, concern. In this light, it is no wonder so many courtiers had affairs out of wedlock; illicit romances were a primary way of satisfying passions that too often were not fulfilled by a spouse.
The Princess of Cleves is markedly different from her female peers at court principally because she has an innate, uncompromising sense of virtue and loyalty in love. After a 'marriage of convenience' to the Prince of Cleves, the young Princess determines to be dutiful and obedient to her husband even though she doesn't love him. However, when she meets the Duke de Nemours, they experience love at first sight, and the Princess grapples with her heart and conscience to resist the temptation of an affair. This sets her apart from other women of her era, who would have unhesitatingly followed through on a whim of passion. Although the Princess is resolute in never having a physical relationship with the Duke, she is unable to purge her feelings for him, which feels like a betrayal of her husband. This prompts her to reveal a further, uncharacteristic behavior for women of her time: total honesty. She admits to her husband that she loves another man and asks to be sent into seclusion to avoid seeing the Duke in court. Her commitment to battling her heart and body for the sake of duty is admirable -- and also tragic, as it causes her own and her husband's death from heartache and unfulfilled longing.