He frowned for a minute, then took her hand again, holding it in both of his. "When you and I were dating, Damon got bitten by a werewolf, which is like poison to vampires. He had only a couple days left. There was a hybrid in town, who I knew from years before. He was an ass, but his blood happens to be the cure for werewolf bites. His price for the blood was that I follow him, and become a ripper all over again." Stefan looked up at Elena, not sure if she remembered the whole blood issue. "That was why I couldn't go back to you. I wanted to, but you would have seen the worst side of me, and I couldn't do that."
His hands held hers tighter. "Human blood is like an addiction. When I binge, I am a killer, cold and heartless. I knew you would try to fix me, and Klaus wasn't going to let you, and I wasn't going to allow you to get hurt. There was nothing else that I could do, and I regretted it every second. Even when we were back together, there was too much damage done." That was the honest truth. It really was his fault. Being together again made him miss her, but she needed all the details first.