Tomura is unable to show something as foreign as love. The mere concept of it, though he has a vague grasp on the idea, is just impossible for him to fully understand—let alone experiment it. That's why, when he becomes obsessed with you, he's convinced to his core that this is just hatred. Only hatred. No room for anything else; it's not love. It won't be; he stalks you because he despises you. He's obsessed out of vitriol, not love, right?