She knew he didn't love her.
But something inside of her always insisted that he did, and that he always would. That was why she'd give him anything: her time, her virginity, her life, her soul, her sanity: she would give him anything, just to try and make him happy.
Just to try to get him to love her.
Just once she wished he would show the need to have her, a true need, not one of his false proclamations of how he needed her to help him rule the new world. She knew. She knew that when he said that it was a lie, but she never verbalized this to anyone. Perhaps she wanted to make herself believe that it was true, that she was wanted by him. That he saw her as something more than a hopelessly blind follower, the sacrificial lamb.
Maybe if she did as he said, just maybe, he would come to notice her, to appreciate her, or so she tried to make herself believe. Any attention would do really, any attention besides the lies and empty sweet-nothings he whispered into her ear. Whether the attention prompted him to cover her in sweet kisses, or to search her porcelain skin invasively with his hands, or to even pin her down and stare at her with a hungry, predatory look in his eyes. Anything, anything would be better than the lies he fed her, whether it be true attraction, or an abusive lust that would leave her body covered in angry purple and black bruises.
He was her savior, her avenging angel, her God. For him, she would do anything, anything for him to even think of her with a third of the reverence in which she held him, or even less. But she knew he could not, or rather, would not do such a thing. Yet she could not bring herself to leave him. To him, she may have been dirt, but he was her God, and to separate herself from him, to leave the basking light of his glorious image would be to die.
That's why whenever he held her loosely, and said in a stoic, uncaring, and untruthful voice that he loved her, she smiled, but only half believed it. The rational side of her would deny it, warn her to leave, that his love was a lie, and she would never be wanted.
But rational thought always lost to emotion. She was an emotional person; it was what drove her, and the need to be around him, to feel his presence was essential to her life.
This is why Misa would only smile, and giggle, holding his tense form closer to her body, and bury her face into his warm chest.
She was hopelessly devoted.