Answer:
The three lines that reflect Satan's apparent regret are:
"Of bliss on bliss, while I to Hell am thrust"
"Where neither joy nor love, but fierce desire,"
"Still unfulfill'd with pain of longing pines"
Explanation:
John Milton retells the story of Adam and Eve and how they were expelled from paradise in his poem Paradise Lost. In the excerpt we are studying here, Satan is, at the same time, rejoicing and suffering. Even though he was able to tempt Adam and Eve and have them eat the fruit from the forbidden tree, he still envies them. Despite being now sinners, Adam and Eve have each other to love and care for. They'll be in each other's arms while Satan must go to Hell. He will never experience love, he shall never be fulfilled. That feeling is conveyed in the following lines:
"Of bliss on bliss, while I to Hell am thrust"
"Where neither joy nor love, but fierce desire,"
"Still unfulfill'd with pain of longing pines"