He'd offered it to her once before, for entirely different reasons. Then, he'd offered to marry her, mistakenly believing she had been asking him to father a child with her.
He hadn't offered then out of duty, or a sense of obligation. That's not why he's offering now. Wait, he is offering, isn't he?
He looks slightly bewildered, at her hand, as he takes it in his, at her face. "Isn't what?"