After weeks of noticing that something was wrong with Algernon the doctors finally decided to test him and noticed that his brain had gotten smaller and It was deteriorating.
A few days later Charlie found Algernon dead in the lab and decided to bary him in the ground by a tree with flowers.
In this scene Mrs. Kinnian is helping Charlie cut his hair because his brain has been slowly deteriorating and he can no longer due it himself. He is no longer self sufficient and relies on others.
In this scene Charlie is expressing himself to Mrs. Kinnian telling her that he can no longer be in relation with her because he can't take care of her. He is afraid that he will die on her like Algernon died because of the experiment.
After about a week Charlie became anxious with staying smart. But finally after he saw that know one could make his gains last he just decided to live with it. He went back to the factory and got his job back and everything went back to what it once was.