In the days after Jenny's murder, Buffy began offering herself to him. Not overtly, or with words, perhaps not consciously, at least not at first, but subtly, in the way she stood a little closer to him than usual, always turned towards him, her head slightly tilted sideways, her shoulders back, her neck and chest open and bare. In the back of his mind Giles noticed the change in her body language, and didn't know what to make of it.
Then, one time, when he was intending to reassure her that everything would turn out all right, he placed his hand on her bare shoulder and it became clear to them both that this was what she wanted. It would be her apology for failing to save his lover, her penitence for setting a monster free; she would give her body to him as a kind of sacrifice.
She closed her eyes and her posture became yet more submissive. Her expression changed almost imperceptibly, but Giles could read it. He could tell that he could slip the strap of her tank top off her shoulder and she wouldn't object; he could slide his palm over her breast and she would sigh like any other man would want her to.
He drew back his hand like it had been burnt.
Buffy frowned; she wanted to make amends with him, but didn't know how.