It's all a lie. A story he made up in his head. Just a little something to distract him from what he really wants. In the day, he loves her. He yearns for her. Every time he sees her after a long day, his stomach gives a little lurch and he runs to her; he can't wait to wrap his arms around her and rest his face against the little crook of her neck.
In the night, when he's fucking her, and when he should be thinking of nothing but her, and her body, he doesn't love her. He has to bite his lip, to make sure he doesn't yell out her name instead of the woman beneath him. In the night, when she's sleeping curled up next to him, he thinks of someone else instead.
He's got everybody fooled except for himself.