What advice does Gretel give Bruno and what is her reason for giving it? Do you think she realizes what´s going on? Why / Why not?

Gretel advises Bruno to stop talking to his imaginary friend. She tells him it indicates he is going crazy, but he tells her he doesn't want to stop. Gretel reassures him she won't tell anyone about his imaginary friend, and teasingly tells him she has her own. When he asks her if she's telling the truth, she scoffs, "I can't afford to act like a child, even if you can" (159) and leaves the room. I do not believe that Gretl suspects that Bruno's imaginary friend is real.