Unreasonable

I have heard this term umpteen number of times. Unreasonable.Dont be unreasonable. Dont demand unreasonably. That's an unreasonable deal. Blah, Blah, Blah.....
What exactly is being unreasonable? Let's try and find out. Shall we?
G.B Shaw says that ""The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man." Thats Shaw. Its true, that if we behave in a reasonable manner we accept things as they are and loose the power to change them. But I wish to touch the aspect of relationships over here.
Unreasonablity is always there a pure love relationship. This is because Love itself is unreasonbale. But that on the positive side is enjoyed by everybody. If a husband buys astronomically expensive gift for his wife, he is being unreasonble. But the wife sure enjoys that.
But when that unreasonablity strikes on the negative side, its not acceptable. What is wrong if the same husband behaves in a manner that is not logically acceptable?
It exists in each and every relationship. If people learn to accept, there will be no divorces and fights over petty issues. As they say, you tend to hate them the most whom you have loved most in the first place.
Try being unreasonable and accept the unreasonablity too....