A marriage is taking and giving your whole heart, mind, and soul to each other. This is a very hard and serious commitment. The regular vows try to say these things, but it up to the two involved to live a life of these vows.
God simply wanted persons in a relationship to keep the other a higher priority than they keep themselves. This is a two way street, both have to work at it every day, a constant effort.
You know man's way, a way that includes laws concerning taxes, end of life and medical decision making, what to do with estate matters should one die without the other, etc., etc., etc. God wants you to know He will take care of your needs, so you do not keep nagging your spouse to "please" you and visa-versa.
The marriage (and your next 50 + years together) is just between the two of you, the reason for the ceremony and clergy of some sort is your "coming out party". It is a public thing, a way for the rest of "them" to get used to the fact that the two of you are commited to each other. Does God care if you have a formal wedding to see you as a married couple? No. Does God need you to file jointly on your taxes to see you as married? No. What does God want? Your commitment in your heart(s) to each other, for better or worse, richer or poorer, in sickness and in health. Unfortunately, most if not all marriages will see all of these conditions, and want a pre-nup to walk away when being married isn't fun anymore. God loves you no matter what you have done, no matter what you have become, can you (will they) love another no matter what they have done, no matter what they have become.
This daily commitment and effort is what God wants, your priority of the other higher than yourself, service and ministering to the other for the long haul are the hallmarks of a great relationship that others (maybe even you) can see in others. This is a very serious matter, God wants you to take it this seriously, because when it is all said and done, only the three of you will know whether or not you had a real marriage, outside of this trio, no-one else should be as interested in your marriage's success. Concerning this trio, you NEED Him in this marriage for it to succeed. Period. Without Him, your marriage has not got the foundation to withstand the storms that will come upon it. Temptation is everywhere, Satan is very interested in your being unhappy and fighting. Satan likes divorce and spouses that walk out when things get difficult. You NEED God involved to help you in the good and bad times, the happy and sad times, the rich and poor times, the healthy and sick times. Leave Him out and figure Satan will come in.
This all seems so involved, but marriage is involved. God wants you two involved this much because no matter the millenium you are living in, marriage is a tough job.