Why is it that Mary was able to pretend fainting before but she is unable to do so now?

Mary may have been able to pretend fainting before due to a combination of confidence and the context of her situation, which allowed her to convincingly mimic the behavior. However, her current inability to do so could stem from increased emotional stakes, a lack of practice, or the awareness of the consequences that come with such an act. Additionally, her mental or physical state may have changed, making it harder for her to feign such a response convincingly.