Map, conceptually what you are saying is valid but i think your application is wrong. The reason is you are applying your concept to "change" another concept called MARRIAGE.
The concept of MARRIAGE, as very correctly explained by Cindy, is nothing but a contract that promotes a sense of security in both the parties. Now, this contract is being used almost in the same form all over the world. And this IS MARRIAGE.
Now, just as there are different kind of companies such as LLC, Inc. etc. you can have different kind of contracts for relationship as well. Choose what ever suits you the best. In your case, you are defining a new type of contract. But you can't change MARRIAGE. If it were a variable, you could call your contract as MARRIAGE2
but not MARRIAGE.
The contract of MARRIAGE == Love + Fidelity + Expectations + other things.
The contract of MARRIAGE2 == Love.
People of the world have overwhelmingly chosen to enter the contract of The contract of MARRIAGE. However, that does not mean it is 100% correct/without flaws. But then, so is the contract of MARRIAGE2. It will have it's own deficiencies.
So what I want to say is set an example by entering your contract and propagate it...who knows, 10 or 50 or whateever years down the line, the contract of MARRIAGE might become obsolete!
And again, you cannot redefine MARRIAGE.