Though you might have gotten along well at first, after a while you find it increasingly difficult to communicate with each other. Your criticisms of your partner stack up and create resentments within them, and could deplete their self-esteem. As you know each other better and better, they could start to think that you're more prejudiced or conservative than they originally realized, and they want to challenge those limited ways of thinking.
You're hard on their ideas, and as time goes on, you establish a pattern of challenging their intellect more and more. You could think within yourself that this person is smart and knowledgeable, but you project the feeling that you don't think they're very smart at all, or capable of making good decisions in life. What a limiting influence this could end up being! However, it doesn't have to be limiting. In fact, your lover may use it as a chance to become more thorough in their thinking, more dedicated to their own path in life and their own ideas. The kind of challenges you present to them requires them to state their case and defend it. While this is likely tiresome and even annoying, it could prove an important part of their personal mental development. If, through this experience, they end up being a more effective communicator, then they have gotten something useful out of the tension that exists between you.