“Without denigrating the noble vocation of marriage, it can rightly be said that the couple undertaking marriage can find no better guide to understanding the essential nature of the gift of self than the celibate priest who has emptied himself in imitation of Christ.”
The problem in a marriage is that not only is the human a sinner, but the marriage partner is a sinner as well. If both partners are trying to make the marriage work, saving it usually is not that hard. But if only one of the two wants to save it...
That's a key point. When people say a marriage "just fell apart," they're being deceptive. If a marriage doesn't last, it's because one or both people weren't willing to do the work to address their sin and hold on to something bigger than themselves. It's not because of the weather or other outside factors.
Also boys and girls, priests are taught in seminary about all subjects relating to the people they will minister. You don't have to be a rapist to council rapists, do you? You don't have to be depressed to council the depressed.