Why do you think Bryon had lost at the end of the novel?
The original question had to be edited. Examining how Bryon feels fundamentally alienated is one way in which Bryon could be seen as having lost at the end of the novel. Bryon loses at the end of the novel because he is emotionally cut off from everyone. He is no longer able to demonstrate care for Cathy. Additionally, he must recognize that as Mark uses Bryon's own words against him, there is nothing in that relationship towards which he can return. "That was then" and "this is now" is where his relationship with Mark lies. Bryon must sojourn alone into the world, without anyone to assist or to guide him.
It is here in which a case can be made that Bryon had lost at the end of the novel. Bryon has matured emotionally and has recognized what is right and what is wrong. These are priceless lessons that will guide him. Yet, he must also acknowledge that he holds these lessons without anyone to accompany him. The human constructs that defined his world are now gone. "That was then, this is now." It is in this rather harsh assessment that a case can be made that Bryon had lost at the end of the novel.