she's a terrible person but she's not completely dead inside. She knows how much Tom loves her and she's operated under the assumption that he will no matter what. She's not only the alpha but she considers him inferior intellectually, and status wise. (basically she can upgrade. he can't) At the same time she genuinely seems to care for him, as much as someone like her can, appreciates how much he has her back. this was the first hint she could actually lose him.