Answer:
Because the apartment reminded her of something about Martha's past that worries and bothers her, something she can't bear to remember.
Explanation:
"Martha Martha" is a short story that tells the story of Pan and Martha for an apartment that Martha can rent before starting her graduation. Pan is the real estate agent and seems motivated to help Martha, since she was curious about the girl and the way she behaves.
Martha seems to be hiding something and in fact it is, but we only realize this, after she panics in the yellow apartment and wants to leave immediately. We did not know the exact reason for this behavior when we read the story, but we learned that the apartment reminded Martha of something serious and disturbing about her past, something that she cannot bear to remember.
