And on the flip side, why should adults perpetually put aside how they feel and sacrifice their peace of mind and happiness and suffer in misery just so their children have a stable home?

My parents split when I was 4 and I remember them fighting all the time. It was not peaceful at home. NONE of us were happy, and while it sucked to have my family splinter at such a young age, BOTH parents were far happier after the split, which meant that I felt calmer and more stable--and yes, happier--in turn.