Security, for you, comes through an orderly environment, one that you can understand through your personal sense of logic. But when you become intimately involved with this person, you'll sense your idea of what's logical slipping away as their far more freeform, intuitive approach to life unwittingly derails all your carefully established structures. While this won't be a comfortable experience for you, it will be a necessary one, because the buttons being pushed within you relate to long-ago, long-forgotten experiences from other lifetimes, in which your insecurities formed after traumatic experiences.
This person's imagination and intuition will subconsciously remind you of all that you've tried so hard to move away from, in this life as well as in past ones: You have worked to establish systems that you can rely on in your life, so that you'll never again be hurt by someone else's out-there beliefs. But if you pay closer attention to the way your partner's mind works, you'll begin to realize that they really aren't 'out there' at all. If you can treat them and their way of perceiving the world with respect, you'll realize that you can actually blend your own sense of logic with their sense of intuition, for wonderful results. But doing so will mean facing your own fears and insecurities; are you up to that challenge?