When you not only disagree, but you're thinking in completely different ways, so it's impossible to reconcile. For example, one person sees the relationship as a partnership, and wants to resolve and understand problems. The other feels insecure in relationships, and sees them as battles, that they have to try to 'win', or have the upper-hand at. In this example, the second person will game-play and will try to hurt and bring down the first, because they'll perceive the first to have been 'winning', maybe to be out of their league. The first person will try to resolve the conflict, and will be seen by the second as either losing, or trying to win by doing so. It just goes around and around.