The diary helped Anne overcome her loneliness because she had someone to talk to, even when she could not comfortable talking to real people.
As a teenager, Anne is naturally self-conscious. As a Jew in hiding, she is in close quarters with her entire family and another one. Her father gave her the diary so that she would have an outlet for her emotions. She was excited about the diary because she wanted to be a writer.
I hope I will be able to confide everything to you, as I have never been able to confide in anyone, and I hope you will be a great source of comfort and support. (June 12, 1942)
Anne decides to call her diary Kitty, and write to it as a special friend. Even though there are other people hiding with her, she still feels lonely. She does not have any other friends there, and the only girl is her older sister Margot. The diary made her feel like she could pour her heart out to someone without being judged.
In his fatherly wisdom, Mr. Frank gives Anne a diary for her birthday. With this little book of blank pages to be filled with her private yearnings and remarks, Anne has been afforded the friend and confidante that she so sorely needs in such a confining and lonely environment as the Secret Annex.
Clearly, Anne imbues this diary with life as she creates a persona for this diary, and she writes to it in the manner in which a girl would confide in a dear friend. She addresses her new confidante as Kitty:
I hope I will be able to confide everything to you, as I have never been able to confide in anyone, and I hope you will be a great source of comfort and support.
The diary becomes a place in which Anne can reflect upon and analyze the interaction of the occupants of the Annex. Thus, by writing out her observations and feelings, Anne can obtain a certain emotional release which helps enable her to cope with tensions and anxieties that she experiences. For instance, she writes about Albert Dussel, who shares her room. In her April 11, 1944, entry, Anne writes of the problems this resident of the Annex causes with his pettiness. One day Anne has a cushion of his on which she allows the cat to sit. When he learns where his cushion has gone, the fussy Drussel worries that fleas might be on it, and he makes "a great commotion about his beloved cushion."
There is no question that Anne can release her anger or write insults that should not be spoken in the small environment where tolerance must prevail. Her diary provides Anne a "safe spot" to which she can emotionally go and not have to worry about repercussions from what she thinks. With her diary Anne is provided many outlets for her diverse thoughts and feelings (i.e. in one entry she writes a creative piece about her pen). With such a "friend" as Kitty, Anne certainly relieves her lonely and troubled feelings.