You may not have noticed until well into the relationship, but your most idealistic beliefs are incompatible in a subtle way. You both seek personal growth in your own ways, and after a while it becomes clear that you just don't understand each other's methods. You're naturally more intellectual about it -- you actively seek new ideas that you can apply to yourself and your own experiences, and you probably read a lot, talk to different people and so on to actively shape your own ways of thinking and growing.
But your partner takes a more passive and intuitive route than that. They're more apt to feel their way along, relying on their subtler senses to guide them along their path. Needless to say, these two methods of achieving the same thing can be in conflict with each other unless you're each able to respect your differences. You could waste a lot of time arguing over it, asking each other, Why can't you be more like me? The answer is, because you're just not that similar in this one area! If either of you is to achieve personal growth, you have to do it either by agreeing to disagree on your methods, or by doing things your own way even under the pressure of your partner's disapproval.