Why do people give up on each other?

In the last few days I've learned that two couples I care about are splitting up; additionally, reality TV's Mom and Dad of the Year are calling it quits. Of course I'm talking about Jon and Kate Gosselin, the parentals on TLC's Jon and Kate Plus Eight.
I can count on one hand how many times I've watched the show (my students got me interested ... ), but I'd set my stove timer for 60 minutes to remind me to tune in Monday night.
There I sat on my sectional in the living room, riveted to the "couch scenes" whereby both Jon and Kate said something along the lines of "we don't hate each other, but we can't live together because we fight too much and that's not good for the children."
Hmn. Married couples who fight. Married, parenting couples who fight. OK, so what's divorce-worthy there?
All my adult life I've searched for non-combative married people who are parenting (the hardest job on the planet, BTW) and I've yet to run into a couple who are ALWAYS googly-eyed and exhibiting their best honeymoon behavior and never getting bored with one another and are perpetually smiling through life's big and little disappointments and "gosh-golly-gee-whizzing" their way through the week. Puh-leese.
I've been searching for going on 35 years now and I just haven't found that golden couple. I'm fairly certain that perfect couple does ... not ... exist.
There's something called LIFE that prohibits us adults from behaving perfectly 24/7. There's too much month at the end of the money; the dog pees on the new carpet; the three-year-old throws hourly tantrums and screams "You're Not My Mommy!" as you haul her over your shoulder through the automatic doors at Target; your spouse is balding; you are balding; you're tired at the end of a work day and want to go to bed at 7:30; the remote control has gone missing; the flirtatious co-worker is making you feel valued; the in-laws are a pain in the neck; the house needs painting but the Pontiac needed a new transmission and now the neighbors are just going to need to DEAL WITH YOUR FADED PAINT in the subdivision that tells you which colors to use anyway; your headaches (real ones, not the fake sort) preclude any romantic notions; the bank didn't post your deposit on time and now you owe a $25 overdraft fee; the cat killed a bird and delivered it to your doorstep, which your four-year-old has carried into the house with his bare hands; there's a perpetual toilet leak in the downstair's bathroom; middle-aged spread has attacked your midsection; your 13-year-old just brought home a grade card with five F's and one A (P.E.); the stomach flu has ripped through your house and it's two days before Christmas ... .
I could go on. And on and on.
Here's the deal: No one gets through this life unperturbed. Even Angelina Jolie at times is sick of Brad Pitt. And vice-versa.
The show must go on, people. Especially when there are children in the picture.
So, A.L. and B.L., and K.K. and B.K., is there any way to reconnect, to find that joy that first brought you together?
Please try. You're too loving and smart and compassionate to give up on each other.