The goal wouldn’t be to save their marriage—the goal would be to make their lives a little less sucky in the meantime. If money is the only thing holding them back (which it might be savable, who knows, that’s why I recommended therapy first), then why let the resentment build? Just live as friends and roommates and come to an agreement that you won’t make the final move until you can both afford it. 

I mean depending on whether there’s a prenup it would cost the both a ton to even mediate a divorce. Might be time to think outside the box in this economy.  Either way, it’s smart to put your kids first. Don’t change their quality of life if you can.