I know too many who are in essence killing themselves to stay in a dysfunctional family for the sake of kids, though.
QFT. and that sort of thing fucks up everybody in the family - spouses, kids and even "peripherals", like friends.
in my experience of kids and families (from twenty years of teaching/counselling etc.), kids are resilient enough to deal with breaks and splits, but can really live without the sham of two people trying to maintain what is essentially a complete lie of a relationship.
i've had to counsel and/or work with kids whose behaviour has gone fray bentos more often because their parents are staying together and fighting/not speaking etc. than because their parents have split up. and the counselling the latter generally seems to take a shorter time. in effect, it's the "big trauma, but over relatively quickly" versus the "insidious, ongoing trauma, which seems to have no end." i bleieve the damage done is greater in the latter case, too.