Very true.
There are a lot of breakups, though, and I think it's all attributable to the incredible array of choices and dillemas offered by modern life. One party in the marriage will be offered "the big job" at some location the other party doesn't want to move to; one party will return to school and find his or her mindset no longer meshing with the other; one party will go on a "health kick" and get fit while the other remains slovenly; one party will become radically liberal while the other remains conservative (or vice-versa); one party will fall into a group of friends the other abhors; one party will give up drink or drugs while the other continues to imbibe.
The list just goes on and on. We all change so much these days, even in a span of months, that it's difficult to keep it all together. And it's not helped by the number of people who marry for "convenience" or simply to have children, or for money and "comfort," rather than waiting for true love -- which does exist, no matter what the gloom-and-doomers say.
In this, as in a lot of things, it was better in the "good old days."
It was better in the good old days for society, and that's for sure. The disintegration of common moral values, social institutions and law that reinforced them both is pretty near the root of our modern woes. I would say, however, that for the individual (at least some individuals) marriage is still the same as it has always been. I believe that a shared faith is at the core of successful marriages because it touches every sphere of life and provides the ultimate in direction and reconcilliation to one another. Given that preparation, out of the box, very few marriages would fail. Struggles, yes. Contemplation of murder, perhaps. In the long haul, though, they have all the timeless ingredients needed in a healthy and long-lasting marriage. In fact, passing that legacy onto children is, in this secular and unhinged society, maybe the best thing anyone could do for a contribution to life on earth. My $0.02 worth.