Isabella had known many people, had had many friends; and thus if one had the audacity to open a drawer and read her letters, one would find the traces of many agitations, of appointments to meet, of upbraidings for not having met, long letters of intimacy and affection, violent letters of jealousy and reproach, terrible final words of parting (2384).
However, barring all of that, Isabella life had not turned out as intended, she is an old maid, who lives alone and has very few friends. When Isabella looks intot he mirror she sees the truth within herself that she cannot hide.
Here was the hard wall beneath. Here was the woman herself. She stood naked in the pitiless
light. And, there was nothing. Isabella was perfectly empty. She had no thoughts. She had no friends. She cared for nobody. As for her letters, they were bills (2385).
It's funny how we often make assumptions about other people before we even know them, it takes time to truly no someone and even then you only know what they are willing to show. You never know the thoughts and memories that plague a persons mind when there is no one else around. The true Isabella is trapped in the looking-glass, where only she can see her.