Quote 1
"You know how a voice can stir one. Your voice and the voice of Sibyl Vane are two things that I shall never forget. When I close my eyes, I hear them, and each of them says something different. I don't know which to follow." (4.10)
Again, Dorian has a choice between good (Sybil) and evil (Henry) – he's torn between his love for the two of them.
Quote 2
"I love Sibyl Vane. I want to place her on a pedestal of gold and to see the world worship the woman who is mine. What is marriage? An irrevocable vow. You mock at it for that. Ah! don't mock. It is an irrevocable vow that I want to take. Her trust makes me faithful, her belief makes me good. When I am with her, I regret all that you have taught me. I become different from what you have known me to be. I am changed, and the mere touch of Sibyl Vane's hand makes me forget you and all your wrong, fascinating, poisonous, delightful theories." (6.8)
Interestingly, Dorian seems to recognize that he's at a turning point here – he's willing to put Lord Henry's "poisonous" theories behind him and live a good life with Sibyl.
Quote 3
"Then the curtain rises, and you will see the girl to whom I am going to give all my life, to whom I have given everything that is good in me." (7.2)
Hmm…so, if Dorian has given everything good in him to Sibyl, does it all perish when she does?