The words are her undoing, but not in the way it might be expected. Perhaps if she had a better grip on him than just a finger, things may have been different. Perhaps if he'd been anyone other than the love of her human life, another victim of Dracula himself. Perhaps if he'd not offered himself as a willing, loving sacrifice, she'd have taken everything she wanted because of the memory that she couldn't hurt him. Perhaps --

But his words are her undoing, startling Mina deeply enough that she releases his finger and pushes herself away from him as she fights a very literal inner demon.