If you want to answer, what is refusing to settle for mediocre, what is if she becomes equal in this, and what is it exactly that you feel she needs to be for you to have a successful marriage? I'm asking because usually we only get to see one side of the relationship. So if you could put yourself in her shoes, somehow, and ask yourself what it is that is lacking in her.... besides the physical attraction, what changes are you looking for?
Otherwise, I'd agree if you've made your decision and you are not in love with her, then go ahead and leave her. It's best for her as well, other than the other option of her being expected to change who she is.