What does the quote in Book ! mean "I did not love you I went away from you in fornication:

In context, Augustine is speaking to his own sinful nature. He believed that you cannot love sin and love God, and that you cannot embrace worldly notions and friendships while loving God at the same time. It is impossible to do so. This is Augustine's letter to God, his confession to his Heavenly Father.

It seems to me that much of his thoughtful reflection is a comparison of his life and the world to the Bible. For example, in this section, and in the one recalling his theft of the peaches, he recounts the lure of the crowd who praise his wrongdoing. He even goes so far as to say that the voices of the world become so loud as to convince him that the it is “wrong” not to do wrong, i.e. to avoid the “unmanliness” label from the crowd. In his valuing the voices and opinion of the crowd, he gives them power. There are many Bible verses which touch on this theme, but how closely this aligns to James 4:4-10 ESV: “You adulterous people! Do you not know that friendship with the world is enmity with God? Therefore whoever wishes to be a friend of the world makes himself an enemy of God. Or do you suppose it is to no purpose that the Scripture says, “He yearns jealously over the spirit that he has made to dwell in us”? But he gives more grace. Therefore it says, “God opposes the proud but gives grace to the humble.” Submit yourselves therefore to God. Resist the devil, and he will flee from you. Draw near to God, and he will draw near to you. Cleanse your hands, you sinners, and purify your hearts, you double-minded. Be wretched and mourn and weep. Let your laughter be turned to mourning and your joy to gloom. Humble yourselves before the Lord, and he will exalt you.”