Younger women "just aren't sure Clinton is the one"--yes, this seems to typify their sentiment. What they don't realize is that if Hillary Clinton can't get women to vote for her, including young women, then the only woman that will likely be elected President in the future will be a Republican. She'll more than likely be white, will, guaranteed, be a Christian. She'll, of necessity, have to be against abortion rights, and will no doubt be an extreme fiscal conservative. In the eyes of younger Democratic-leaning women, Bernie's pure and untainted. What they don't seem to realize is Sander's political purity is a function of his former political irrelevance. Hillary Clinton has never been politically irrelevant. She's a political pugilist. This scares certain types of women.
Younger women tend to be more psychologically dependent on male approval than women with more life experience. Similarly, married women tend to vote more conservatively. There's nothing new under the sun.