It used to be that marriage was a contract between you, your intended spouse, and God.
Now, it is a contract between you, your intended spouse, and "The State". And therefore when you marry you are giving the State some measure of control over your life.
Last friday I had to stand in front of a judge and say that two people where not living together for the last year so they could get a divorce in the state of Virginia. After 6 months of marriage it took a year, a judge, an attorney, and a witness, plus some cash to finally separate them.
If they had been married for 10 years then there would be Social Security implications etc. Plus I think they still force you to take a blood test ect.
Then why should the state care if they lived together?
It's one thing to have both people say we agree to split property like this it's another to say you have to wait and jump though a lot of hoops to get divorced.
Consider two people that want a divorce, but can't really afford separate households at this point and don't want to sell the house when the economy is bad. Granted this is not the "normal" path but plenty of people get divorced without hating each other.
I would be very surprised if the rule, in some states, of being apart for a year to finalize a divorce, has anything to do with religion/church. Most likely, it is a relic of legislation attempting to define "litmus tests" on which the judiciary can make decisions.
Keep in mind that with things like divorce and child custody/support, couples change their minds (sometimes a lot). Our court systems can't handle this (certainly not the costs). Over the years, our societies have required legislatures to define rules and processes for lumping everyone into a process. I don't think the state really wants to be involved in divorce cases, but there are reasons they are (property, debts, retirement benefits, child custody/support, etc).
Like it or not, state courts have to be involved in divorces. For some couples that can handle it without the courts, well, like education, they get dragged down into the mean.
Now, it is a contract between you, your intended spouse, and "The State". And therefore when you marry you are giving the State some measure of control over your life.