He had never craved the spotlight; his ego had never needed it, but living in the shadows wasn't his cup of tea either.
Here he was, hiding from those who loved him, thoughhe didn't feel worthy of their love. He watched John as the light left his soul and left only a breathing shell that went through the daily routine without his heart in it.
Sherlock had become merely a watcher, living on the outside and for the first time something moved inside him. He cared! He couldn't bear the thought of loss, and dreaded the day when faced with the truth John wouldn't be able to forgive him.
Probably he didn't deserve forgiveness. He indeed had died for them. He had never understood the concept of selflessness, and he wasn't sure if he even wanted to.