Answer:
Anne's relationship with her father is that of a "daddy's girl." She thinks he can do no wrong (unlike her mother) and is completely loyal to him. Mr. Frank is the one person who can get through to Anne, no matter how she is feeling. She gives her father all of the love she withholds from her mother.
Explanation:
Initially, the relationship between Otto Frank and his daughter Anne is a strong one. Anne is very much "daddy's girl" and can do little wrong in his eyes. From her diary, the reader senses that Anne sees a kindred spirit in her father, someone who understands her in a way that no one else truly does.
At the same time, there's a downside to being daddy's little girl. Though she absolutely adores her father, Anne sometimes feels that he doesn't see her as a real person in her own right—that he doesn't see the real Anne beneath the charming exterior of a sweet little girl:
I model myself after Father, and there's no one in the world I love more. . . . But I have a right to be taken seriously too. . . . It's just that I'd like to feel that Father really loves me, not because I'm his child, but because I'm me, Anne.
It's astonishing just how much maturity Anne displays in this letter. She has a real sense of self and who she is. And it's enormously frustrating not to have her emotional development acknowledged by the person she loves most in all the world.
Anne is rapidly developing into a highly mature young adult; Otto, however, still sees her as daddy's little girl. Inevitably, this disparity between their different understandings generates friction between them. We see this in Anne's relationship with Peter Van Daan. As Otto still thinks of Anne as just a little kid, he is deeply reluctant to bestow his fatherly blessing on what seems like just a girlish crush.
In time, it turns out that there's no real depth to the relationship as Peter is much too passive and emotionally awkward to engage Anne's affections for very long. But for Anne, that is beside the point. Otto's disapproval of Anne's relationship with Peter represents a denial of her individuality and her ability to make her own decisions when it comes to matters of the heart:
Why didn’t Father support me in my struggle? . . . He always talked to me as if I were a child going through a difficult phase. . . . I didn’t want to hear about "typical adolescent problems," or "other girls," or "you’ll grow out of it." I didn’t want to be treated the same as all-the-other-girls, but as Anne-in-her-own-right, and Pim didn’t understand that.
Not surprisingly, by the time we reach the end of Anne's diary, her relationship with Otto has changed quite significantly. She still loves her father dearly but not with the same degree of hero-worship she displays at the beginning of the diary. This is an inevitable development, one experienced by countless young female adults at some point in their lives. As Anne has matured, so too has her relationship with her father. The unthinking adulation she once showed towards him was that of a girl and has now been replaced by a more adult, complex, yet still deeply loving, connection between father and daughter.
