The paintings title 'Opening Up' is a play on words. A person could simply open up a book or new chapter or even maybe show your true self, and to trust.  Cain represents Opening Up in this painting by the woman's stance, as a separation of her arms in front of her. 

The book pages used in the painting are from Jane Austen's novel, 'Mansfield Park'   For the books lead character, an early quote from the pages, seems a fry cry from 'opening up'...  "Her manner was incurably gentle; and she was not aware how much it concealed the sternness of her purpose. Her diffidence, gratitude, and softness made every expression of indifference seem almost an effort of self–denial"

....but please read on, there may be a change in heart.