the key factor is making sure that one's spouse is truly a devout Catholic before getting married. The conscience of a truly virtuous Catholic would not let him or her even consider a divorce, and that is more binding that any sort of civil authority. The problem is that most people do not make this their primary deal-breaker when considering marriage.
This is the main point here -- all too many Trads fail to make "they're not a solid, devout Catholic" a complete deal-breaker.
The Catholic Church normally forbids mixed-marriages, requiring a dispensation to marry a non-Catholic, and you still don't get the Nuptial Blessing even if you get that dispensation.
But how many people take that seriously? Or, how many take that rule in the right spirit? I feel sorry for anyone who looks at the Catholic Church like a mean old fuddy-duddy, a spoil sport, someone out to piss on our parade. On the contrary -- the Church is the Bride of Christ, looking out ONLY for OUR OWN best interests. We should trust Her judgment rather than groan at her rules and restrictions. The same goes for God and His Ten Commandments, but I digress...
Unless your sweetheart shows every sign of being a devout Catholic, you shouldn't even consider marrying them. It's true that strictly speaking there are no guarantees. But that doesn't mean you can't increase your chances.
My favorite philosophy: "winners make their own luck". You have to do everything you can. Don't make stupid moves and then blame God, "luck" or "the way it goes" for your misfortunes.
Yes, strictly speaking a person could fall from grace. And yes, strictly speaking any person COULD convert. But that doesn't mean it's "anything goes" and "anyone's guess" on which marriages will last and which will fail.
You want MORAL CERTAINTY that your prospective spouse is a good Catholic, and intends to stay Catholic for life. We can't get scientific certainty, but moral certainty is sufficient to make
a prudential judgment, which is what the decision to marry is.
But as with any prudential judgment, the more information you have the better. That is what DATING is for -- not for "getting away with as much as you can", not for titillating the senses, not for "fun", but to really get to know a person so you can make a good judgment on whether or not they are good marriage material.
It's not that difficult, and certainly not impossible, to get to know someone well in a few months. Just have deep conversations, meet their friends and especially family members, and keep your eyes open. If you are used to loving the truth and embracing it, you will find it as always. But if you're used to deceit, especially lying to your own self, then beware!
- Matthew