My wife and I used to argue about this years ago. The deacon is right that the Church allows it only in a few tight spots like adultery, but in practice a lot of people treat it like any other option. Makes you wonder how many couples even talk to their priest before calling it quits.
My father always said that as soon as there is a conversation about divorce, you should go to the father, and not decide it yourself. The article correctly emphasizes that the Church allows this only in extreme cases, for example, due to treason. And how many couples in our parish are not even asked, they just go and sign again.
