Why does Anne always look at things in the big picture?

She kind of had to.

Really her world was crumbling and horrific things were happening all the time. Ann had to take a bigger approach to keep her sanity. She had to believe that her world would change in the larger scheme of things.

Some people say she was a typical teenager, and in their own way they'd be correct. But what we see in her writing in something more than a one-sided depiction of a horrific experience.

"I only look at her as a mother, and she just doesn't succeed in being that to me; I have to be my own mother. I've drawn myself apart from them all; I am my own skipper and later on I shall see where I come to land. All this comes about particularly because I have in my mind's eye an image of what a perfect mother and wife should be; and in her whom I must call 'Mother' I find no trace of that image." Sunday, 7 November, 1942, pg. 41

The above quote shows us how she doestanced herself early on. For her, it isn't a matter of what's right in front of her affecting her life; she needs to look at it all, piece by piece, and become responsible for herself.