Sometimes the ratio is reversed. Joe and Jane have fundamentally different views of the world. Joe can listen positively to Jane, and still find that they virtually never agree. Competitors are in agreement with each other. They share the same view of the world.
Competitors can be best friends.
They can also make their products work together. Never marry someone who doesn't share your basic view of the world. If you can't get into agreement with your spouse, you'll both be miserable. This goes for business relationships too. I find that, as a person who was ahead of the times in his twenties, I'm really in synch with them in my forties.