Though you may have entered the relationship believing that you had a lot in common, after a while, it's become obvious that you differ in some frustrating and subtle ways. Neither of you understand the other very well, which lead to feelings of mistrust and frustration. Your grounded practicality looks to your partner more like being a rigid stick-in-the-mud who refuses to take a chance in life; and their intuitive sense of the world and their reliance on their gut instincts look to you like they really don't have a plan -- like they're too flaky to get things done in an orderly, efficient way.
In order to get along, you both have to try harder to get where your lover is coming from. You each have to set aside your skepticism for their way of looking at things, and instead, see things through their eyes. You just might learn that there's actually a lot about their viewpoint that makes sense -- and with hard work, you could eventually blend your viewpoints for an overall greater, more holistic perspective of the universe.