Church-going Catholics actually believe in the sanctity of marriage. Marriage is taken serious by the Church. Most protestants get married outside a church, most by a justice who pronounces them man and wife. What has killed marriage in the protestant faith is no-fault marriages. You can get a divorce as easy as buying a coke, and get married as easy as buying a coke.
The divorce stats in both are very similar for active church goers (I think the Catholic one is a touch higher, but they are larger in the US and that only can slightly shift the percentages).
In both, the pre marriage process is very similar in conservative dioceses/ regions. A test, followed by a relatively long period of counseling. The priest or pastor can and does limit who gets the privilege of getting married in the church.
The leads to a lot of self selection. Couples who do not want to go to that type of Pre Cana preparation will get married elsewhere. Often times, those are the ones most at risk for divorce later. In short, the ones who will not commit to a lengthy pre marriage process may have issues committing to married life at all.
I would love to see a break down of couples who were say, Catholic (or one partner was) and decided to get married elsewhere. I suspect they would tip the stats heavily to the divorced side.
The article touched on this.