His decisions...
The last time he saw her was when she placed her hands on his shoulders and smiled. She had been as radiant as ever and the fear in her eyes was nowhere to be seen, replaced with grim determination. She knew she was marching into the flames and that didn't scare her a bit. She had always been brave. However, the last time that he saw her....Well, she hadn't truly been like that. He could feel how her whole body trembled and he could see how that smile was forced, how she was trying to lie for both their sakes. It broke him inside. The night before, when she had assured her parents and friends that all would be alright, that she had a plan she had been faking that happiness. She feared her next actions. That's why he had told her that he would go with her, into hell and back. She had refused. He hadn't listened and neither had Dream. They would never abandon their closest friend - Fate Existence. She was more to them than she would ever know.
And now, when he could feel the numbness taking over his body and he knew he was dying, he didn't regret that descion. He didn't regret his words when he had last seen her. And more than anything he didn't regret finding her and seeing her. He was content. The last time he had seen her she had been with him and that was enough.