I will not be getting married in government sanctioned union.
I will create my own agreement with terms and conditions mutually agreed to and the government won’t be informed.
You can try; but in the event of divorce, the law of the land trumps individual agreements. That's one reason why the palimony case of Lee Marvin and Michelle Triola back in 1977 was the death knell of traditional marriage in American law. "No-fault" divorce, first introduced by the Bolsheviks, also undercut marriage; and by the way, two California "innovations" in family law -- no-fault divorce and legalized abortion -- were signed by Governor Ronald Reagan. Even he did not foresee the terrible consequences.
Now we have little more than a folk institution of marriage; whereas the divorce culture is much more powerful, since that's where the money is for lawyers. Rather like the way our Lawyer-in-Chief is divorcing us from our constitution, religion and economy.