I disagree. Do you have to have the final say with your friends? Business relationships? How about one country vs another? Of course not. You work things out. Same with a marriage.
Your analogy fails because a friendship is not the same thing as a marriage. If you rip apart a good friendship, you might just tear the skin off. If you rip apart a business partnership, it might be a little worse. But marriage should be such a deep and intimate joining that if you rip it apart, you should tear yourself in half and die. If a marriage is not this intimate, then it never should have taken place.
My friends and I are separate entities. Marriage is supposed to be the joining of two people into one flesh, and one mind. All of the examples you cited do not accurately refer to the institution of marriage. I think this is a good example. Our country and the civil war. When our country first was founded, most of the states did want to outlaw slavery then. But a few didn't, and the ones that did let it slide. A few decades down the road, that one difference that should have been dealt with in the beginning is spiraling out of control. The country is being torn apart. The south is adamant about keeping slavery legal. The north is vigorously opposed to it. There are only three courses of action: The North submits, allowing slavery to continue, the South submits, agreeing to ban slavery, or the country splits in two.
Now, I know the civil war was more complicated than that and there were more reasons for the split. This just illustrates my point pretty well. The states should have dealt with all of their major differences before they got "married"
I think God designed them to be equal.
I think a basic reading of the scriptures would show that this is not true.
But, you bring up something I have been wishing to address.
There is much confusion and misuse of the the word "equal" these days. You and I, Cimics, are equal before the law. That is a good thing. The law should not favor one of us because of a difference in race, color, or creed. But you and I are certianly not just "equal" You are better at somethings than I am. I might be better at somethings than you are.
Heck, you might be better at everything in the world than I am(though not likely

) I wouldn't be your equal then, would I?
My point is that even though the man is the head of the household, this does not mean that he is supierior to the woman, especially before God.
The man should be the head simply because that is the way God designed it. If the man thinks that this makes him supieror in all respects than he does not deserve a wife.
To the extent that equality allows/encourages women to flee abusive men, that's a good thing. To the extent couples break up because of a lack of commitment to work things out, that's a moral failing unrelated to equality.
I agree that women should flee abusive men, that is a good thing. Yes it is a moral failing, often in the form of the man failing to love his wife more than himself, and the woman failing to submit and trust his judgement.
We don't have two presidents, but the president's power is balanced by Congress and the Supreme Court. No one of those branches has ultimate power. Plus, you are naively referring only to a presidential system. In parliamentary systems, negotiations are critical to forming governing coalitions. But let's take it a step further: the church. The pastor does not have the final say in most protestant congregations. Ultimately it is the congregation itself. So, give and take, without a final arbiter is a pervasive part of life.
Yes, the president's power is checked by Congress and the the Supreme Court, but in every possible situation, there is someone who has the final say. The president has these powers: The court has these powers: The congress has these powers: Everyone has authority in an area where the others do not. They do not have "equal" powers. Everyone has his or her "place" in the institution.