Congratulations on the job well done. When two people who are married look at each day of their marriage as an award from G-d then they will find a way how to be worthy of that award. The moment, the marriage ceases to be an award that's when the two stop beeing truly married in the G-d's meaning of it. I disagree with this quite strongly.
Most cultures have an equivalent of marriage, be it official or otherwise.
The variety of different religions involved are irrelevant - men and women make a commitment to support each other. As you can guess, what I'm saying is that the reasons that marriage exists in spite of its shortcomings are understandable, and have more to do with our DNA trying to optimise its reproduction than the word of G-d.