When I was younger and fancy free, I didn't understand why mothers got upset by certain things. I didn't understand what caused conflict between mothers and fathers.
Oh how a child changes things!
When you become a mommy, you get responsibilities and obligations but also a specific set of emotional responses (This is what causes you to cry at Kung Fu Panda 2, for example.). My favorite, however, is the "mommy rage." It is a righteous anger that can only come from being a mother, and all the expectations and duties of such a role.
Let me explain.
Mothers become queens of prioritizing, time management, and therefore productivity. You have to as a mother or you wouldn't get your pants on, let alone your kid's. The result is women are able to accomplish a great deal in a short period of time. There is no such thing as a wasted minute for a mother.
Because of this exceptional time usage, when a child or husband says "I was busy" or "I didn't have time" a mother will laugh (if you're lucky) or become enraged. Inevitably the person giving an excuse can ALWAYS be countered with, "Really? What were you doing today? I woke up at 6 AM, did all the laundry, the dishes, cooked, played with the baby, pumped, changed 8 diapers, fed the baby 8 times..." Etc etc. Oh! It's especially good when mother is sick and STILL does all this. That's my favorite!
Now, it's not that we begrudge doing these things. Mothers love their babies and take joy from caring for their babies despite the thanklessness of such tasks. Rather it's the imbalance of activity that pisses us off. It's the fact that our share makes it very difficult for us to get "me time" or any of the things we'd LIKE to get done. So on top of not being affirmed for our value and importance, we also don't get breaks because the father doesn't feel comfortable soothing baby or just takes time to himself without asking or negotiating a break for mom.
Probably there are some men who are able to avoid mommy rage by shouldering a greater portion of childcare (SAHDs for example), but it is a LOT harder for men. This is because of a difference in priorities (and probably hormones).
Now, I don't doubt that many dads out there LOVE their kids. I don't doubt they do most of the things they do for their kids. But to compare this prioritizing to a mother's is kind of like comparing Mack Trucks to apples. They're not even in the same category.
Women change during pregnancy. Suddenly all of our choices are made based on what our child needs. Our emotions, hang-ups, and even personal needs no longer hinder our decision making or dictate our schedule. If something needs to get done, it gets done *now.* Not later, not tomorrow, *now.* If the baby's crying, everything else comes second. Personal misgivings about career choices etc are pushed aside to insure baby has everything he needs. If something or someone gets in the way of baby's needs, they are removed. Period. Baby comes first.
Men don't have this urgency and drive like women do. There isn't a switch that gets turned for them during pregnancy. They have to learn these things (some never do), and it's a process (which for most mothers is frustratingly slow - thus the mommy rage).
It's a recipe for conflict.
When men (and women) recognize this difference and work through it, things go much more smoothly and parents can avoid the mommy rage - at least they can most of the time. And while the righteous anger will show sometimes, overall mommy will be happier, and if mom's happy, so is the rest of the household (You know, rainbows and puppies everywhere. Everyone's room is clean etc.).
Ah! Beautiful familial bliss! It's not just in fairytales! It is possible! Well, at least moderate familial contentment is, with some understanding and direct action from all parties involved!