With this aspect between you, a fun, happy, smooth relationship is a pretty remote possibility. The problem is, you're too much of a mixture of power and rebellion -- you cross each other at every turn, and you could really set each other off if you feel like your lover's getting in your way. Nothing is ever accidental or mild between you; if you unintentionally upset your partner's plans or create an obstacle, they suspect you of doing it on purpose, and it's a big deal.
You both have a lot of plans and ideas, and you don't want anyone getting in the way of them. But your biggest, most important causes are at odds with those of your lover. You two take two different corners of the ring on almost everything that's important to you; it's like a developer versus a conservationist, or a war protester versus a decorated Army general. You both take a firm stance on what you believe in, and you feel so passionately about your own position that you almost aren't even able to hear each other out or understand anything about each other's point of view. Needless to say, that kind of fervent passion for a cause can sap the passion from a romantic relationship. It takes an awful lot of extra work for both of you to keep your partnership strong.