i would suggest when that situation arises, try your best by attending marriage classes that teach the difference in unequally yoked, the born again meaning to stay married.
Okay, so without looking like I'm setting a trap, I would simply point out that marriage counseling will not save the unsaved spouse. Saying that a marriage needs counselling sessions simply because one person is a non-believer , would, in my opinion, set a dangerous precedent.
You are not alone in this thought, however. Many preachers espouse the idea that a marriage isn't whole until the other spouse is saved. This gives the greenlight for many young Christian women to pick up and leave due to "righteous conviction."
The church typically will side with the wife stating, "We feel your pain." After all he must of done something horrible to her since he's a non-believer.
But unfornately, the most horrible thing done here was to the children by separating them from their father. And in most cases, he will be traded in for a new one.
The children come away with at least these three assumtions when they get older:
1. Christianity is a farce since no one stays together anyway
2. According to the Bible, my mom is an adulterer and a hypocrite
3. Marriage stinks, so it's best just to live together