In reality that happened: the royal mother in law and father in law lunched with the couple the day after the wedding and gave her the money in public. This troubled young Elisabeth so much that she never forgot the issue. We must remember she was only 16. She was so embarrassed that she kept a fear for sex all her life. Perhaps this began to appear as a trauma. Also the constant meddling of her aunt and mother in law. As you say, she kept all her children away from her, critiqued her teeth and manners (which she considered inappropriate for an empress), and when Sissi finally went to Venice with her husband and children, her eldest daughter died, and the mother in law blamed her for that unfortunate and premature death. She never recovered.