DesignDawg,
While I understand where you're coming from, I think you are missing the point. The point is those marriages were not meant to be. They were not in love. So the plot is that true love prevails over marriage. People do make mistakes and get hitched to the wrong person. Staying together when they don't belong together could be an even bigger mistake.
Of course children would complicate this issue. But on the Frasier show they didn't have kids as far as I know. (I didn't see the movie so I can't comment on that)
Anyway, the world isn't going to hell because some marriages fail. It is going to hell because of violence and other evils. (see unxpurg8d's thread)