Through the years I have seen divorce destroying families of friends and relatives, sometimes from close by. Just yesterday I heard about another marriage biting the dust. Yet the way people talk about such things is as if nothing of value was really lost, sort of "yes, it's not how it should be, but, after all, he was so difficult to live with." It often changes rapidly when their own child or sibling has become the victim of cruel abandonment, which is really what divorce is all about.
Now, since I'm not of a Catholic persuasion, I don't view marriage as a sacrament, but more like a contract which could be dissolved in some cases. The traditional reasons for fault-based divorce are abuse, abandonment, adultery and addiction, and I'd add to those an able-bodied husband willfully refusing to provide an income (which is a form of financial abandonment), and a spouse denying the other one marital rights without a good reason,e.g. health (an abandonment of the marriage bed).
Even if there is a reason there should be some waiting period before the marriage is officially dissolved (the spouses could be separated during this period, especially in the case of abuse), as it still is in countries like Germany (they used to have a waiting period of one year in the mid-2000s though I'm not sure if feminists haven't abolished it since, as they have been trying).
However, discovering after 20+ years of living together that you aren't really in love, or have never been happy, or some other bogus stuff along these lines is not really a reason and it will never be. As I have mentioned in one of my previous posts, even in pre-Christian times Germanic tribes considered oath-breaking (and that's what you do when you break your wedding vows and leave) one of the most despicable crimes worthy of the worst torments of Hell, while nowadays we are taught just to shrug our shoulders and move on.
Imagine if we talked about murder in the same way: "Well, I do believe murder is kinda bad, but you know that neighbour was really such a pain in the neck. He never parked his car properly and once I even saw him kicking his dog. If that wasn't abuse, I don't know what is. And, after all he was killed in humane manner and didn't really suffer much, so I can't really blame the person who did it. We are all human, you know and the Bible says something about 'judge not' ". Does it throw chills down your spine yet? Well, the society which not only condones, but positively encourages and cheers divorce and adultery, can very well legalise murder soon.
Conservatives in the USA and other countries have been fighting a losing battle against SSM but usually turn a blind eye to the topic of divorce, which is an example of shameful cowardice as ever was.
That said, the best way to avoid a divorce is to invest time and effort into cultivating a good relationship. After an initial period of romantic love, something else ideally should be growing, something more akin to companionship and even friendship, though it's important not to forget that even as you get older, you spouse is still your romantic partner and not just a walking ATM/ the mother of your children or a buddy.
Never take your spouse and marriage for granted, and if necessary, fight for it. It's well worth it.