Your partner's emotions will confuse you, and this will likely only become more pronounced as your relationship progresses. While their emotional intensity may be part of what initially attracts you to them -- after all, there's nothing like a little bit of jealousy and possessiveness to make a relationship feel more dramatic! -- it will also be one of the main factors that begins to frustrate you more and more as time goes on.
You just won't understand why they are so impassioned. The problem between you will most certainly be a karmic one -- too many old connections now submerged in the layers of time. In another lifetime, you may have been lovers who had trouble understanding each other. Or you may have been two people firmly in separate camps regarding some political or scientific endeavor with no effective way to communicate about your perspective, because you lacked any frame of reference with which to understand where the other was coming from. In this lifetime, you'll feel that same strain whenever your partner feels something strongly and you simply give them that blank stare, or you think that your reasoning is perfectly sound but they accuse you of over-rationalizing the situation. Rather than letting the frustration mount, you should try to transform the way in which you communicate with each other. You must try to listen empathetically to them; even if you can't directly relate to their feelings or experiences, let them know that you value their perspective anyway. It's quite possible that you'll become a deeper and more feeling person through the course of this relationship.