Arthur was once and the future king. Merlin was once and future warlock.
Merlin stood in front of Arthur's grave. He couldn't cry anymore. Tears couldn't give him relief. Not in that case.
The sorcerer loved the blond man as friend and even more. However he had never said it to Arthur. King had his queen that Camelot needed. Although she had betrayed him.
Merlin would never do such a thing.
The most powerful warlock all over the world felt like scared boy. He lost everything what was worth in his life. His soul's life ended with Arthur's last breath.