Some parents convince themselves that it's not bad on the kids because they don't want to feel guilty about what they're doing. It's a selfish mindset. When they're old enough, the kids realize that the parent who left was willing to give up half of the time with them that they used to have. That's hard on kids...to know that their mom or dad placed less importance on them than on threir own selfish wants. And kids do realize that.
"Always go straight forward, and if you meet the devil, cut him in two and go between the pieces." - William Sturgis, clipper ship captain, 1830's.
