Charles can tell that
Sarah wants him to leave, but he’s determined not to. Her eyes show independence, a dislike for sympathy, and determination to be herself. Her eyebrows are strong, but her face is very feminine. Her mouth is sensual. Overall, her face doesn’t go with the fashion of the time. It reminds Charles of foreign women whom he’s slept with. He’s beginning to guess at a darker side of Sarah. He’s slightly repelled by this, as most men of his time would be. However, most men would blame Sarah for this part of her nature, but Charles doesn’t, because Darwinism implies that morality is hypocrisy and duty completely unimportant. Furthermore, Charles has read
Madame Bovary. He stays because Sarah suddenly reminds him of Emma Bovary.