Responses
I don't think anybody exactly understands the meaning behind why the ending is the way it is. However, I think at the end he was grieving the death of the Doctor. If anything the grieving was quite obvious, but at the very least, we know that Clark cared very much for the Doctor. I'm sorry for giving an explanation as such. Perhaps he was regretting getting involved with Alex.... Well, who knows?

This is freaking good. Im very satisfied with the ending!