The most probable outcome is that the new expenses will exceed the old by a significant amount. In many cases the only answer is to work more to increase income. But, remember that additional hours at work will mean additional costs for day care, fast food, etc. Ultimately, only Mary and her husband can answer the question of who should bear the burden of supporting two households. Sacrifices will be required.
Studies frequently point to money problems as a major cause for divorce.
If that's true, then divorce and the increased expenses that come with it might not be the solution that many couples are hoping to find. We'll leave the marital counseling to others. Anyone who attempts it will need financial facts to go with the emotions that come with divorce. Failure to plan now could turn a bad situation into a disaster for everyone. Thanks to Mary for an interesting question.