I honestly think that the source of dissatisfaction comes with the idea that one SHOULD have it all in one lifetime. Whereas it's not possible. For parents who have kids and thriving full time careers, they sacrifice time spent one on one with the child. The grasping after the idea that we could, nay should, have a perfect life with zero tradeoffs is what causes dissatisfaction. Whereas if we made our choices with the clear eyed understanding that in making one choice you are closing the door on another, perhaps we would be more satisfied with our choices? More satisfied with the present moment in all its imperfect glory?

Also I'm sorry but people who desert their children, whether mothers or fathers, are selfish, if they're doing it simply because they "are tired of it and want a more interesting/exciting life". The fact that women are held to a higher standard about it sucks but we should hold men to the same standard and usually do (deadbeat dad anyone?).