You're very Catholic, aren't you?

So this couple would continue an unhappy marriage till they die just because they had a kid?
Since Stan and Donna are still together, they had real feelings for each other. Anything genuine, I can't be against.
Also the nature gave most species the tendency to mate with other males/females so that there is more variety of genes and better evolution. But of course human beings are a bit different. I'm not saying we should look for other gender to mate and reproduce, it is not practical for bringing up kids. I would stick with my wife as long as we have bound as a family but if that house is a hell every day, it is not good for anyone. I'm sure Stan's wife is happy now that it all ended. She was hurt of course then.