the portrait: rejection by sybil

Dorian has almost instantaneously 'lost' his love for Sybil. He can't explain it, but somehow it seems to stem from her horrible performance (which embarrassed him in front of his friends), and her declaration that she could no longer act because she'd found reality with him. Dorian walks the streets all night, not understanding how easily he's become disgusted by the woman he'd loved only hours before. When he gets hope, he happens to look at the portrait, and in it he sees an unexplainable change in his expression. The change was "a touch of cruelty in the mouth," and for him it symbolized what he understood was his cruelty to Sybil, and yet excused because he believed the fault lay with the cruelty of her bad acting.