Despair
He held her in his arm like a broken toy. Confusion and despair filling his mind as he tried to comprehend what had happened. He was always so aware of her. He had been so careful. How could he have let this happen to her? She was so small, so delicate, so human. He was supposed to protect her. How could this happen?
He pulled her limp body against his chest, holding her as close to him as he could, fighting off the painful tears that were burning his eyes. He never got to tell her he loved her. He was always so scared of it. She was human, he was demon, he knew there was no happy ending for them but this? This was his worst fear. If he knew it was going to end like this, he would have never spoken to her to begin with. He would have sacrificed every happy moment she gave him if it meant she got to live the rest of her life.
He gently laid her body down on the rocky ground. There was no question as to what needed to be done. He was meant to keep her safe and he had failed. He had failed at the only thing that mattered. He unsheathed the dagger that hung on his belt and let the tears escape.
He was almost immortal; he always loved that. He could live forever if he wanted. The only thing that could take his life was this dagger. This shiny, emerald dagger with the beautiful iron hilt. He always kept it with him as a precaution, so no one else could use it against him. But now it was his last option. He admired the blade for a few seconds before plunging it into his heart. He laid himself down beside her and stared at her delicate face. How could he let this happen? His vision began to fade but the despair never did.