In a past life, you were close with this person, either as lovers, partners or friends; and in some way, they demonstrated that they were fundamentally different from you in the ways that they thought about and perceived the world around them. The differences in your thinking led to a painful separation, and that disappointment and rejection that you felt has carried over to this life. If you become intimately involved, you may start to notice yourself exhibiting almost automatic disapproval when they try to tell you something they're thinking about.
Even insignificant conversations -- something they find funny, or what they're planning to do with their day -- will hit your internal buttons and make you frown. You'll criticize their ideas and push them to think more logically, more realistically -- in short, more like you -- because deep down in your soul, it will feel threatening to you anytime they exhibit their independent thinking. This will actually be a good lesson for you to learn: that of establishing a close, intimate connection with someone whose mind works very differently from your own. You'll have to talk out your feelings of vulnerability, though, and continually remind yourself that when your partner says something that's not what you expected, it isn't a declaration of rejection or division between you.