You find that you're at odds in the way you think, communicate and approach life in general. You're just such different people, with personality traits that seem to be in conflict. Your partner naturally possesses a more forceful, dominant personality than you do, and could find your more introverted or cautious approach to life to be a hindrance to their naturally high energy.
You could also feel overwhelmed by your partner's seemingly aggressive communication style, and might respond by retreating into a protective shell that cuts off any possibility for understanding. It's likely that you both are more attuned to the differences between you and to the qualities you don't like in one another than you are to your similarities, or to the qualities in one another that you respect or appreciate. This is simply a natural, if unfortunate, focus for you two. However, a relationship between you could have an overall positive effect -- it could force you to examine your own natures and make conscious changes in the ways you meet the world. For example, your lover, who is likely the more dominant partner, could learn that their style of communication really is too harsh or aggressive for you, a more sensitive person, and could learn to tone it down; and you, who are more reserved, could learn to broaden your mind and assert your personality in a more positive way.