THEY TAKE OVER YOUR LIFE
Puppy and novel are both massive time-sucking vortices. Their needs expand to fill every waking hour. Your daily routine is bludgeoned to death; your entire life is now THE NOVEL. Or THE PUPPY. If, in a sad attempt to snatch two minutes for yourself, you ignore the puppy, she will pee/vomit on the couch/pull down the bath towels, shred them and eat the carnage. And then vomit on the couch.
Since novels don't do any of those things, you may think you can ignore yours with impunity. hahahahaha You can't. Because:
THE GUILT...THE GUILT...
It doesn't matter where you are. It doesn't matter what you're doing. If you're not working on the novel, then a little voice is yammering in your head: Chapter 7 isn't going to write itself, you know.
"But I HAVE to renew my driver's license/buy groceries/go to work!" you cry.
Not if you really loved me, Novel says. Not if you were REALLY dedicated.
Puppy races around the house with a half-demolished remote control in her mouth. "No! Bad puppy!" you shriek, as you pry crumbling bits of plastic from between her molars. Knowing that if you'd just sucked it up and taken her for a good run this morning, even though yes, it was raining, she would at this moment be tired and napping and not looking at you as if you've just stomped the last bit of joy out of her soul.
Face it. You will never be good enough. Learn to deal. Also learn to put the remotes away. And anything else small enough to fit into Puppy's maw. If something looks too big, put that away too. Puppy likes a challenge.
IT DOESN'T MATTER HOW MANY TIMES YOU'VE DONE THIS BEFORE. YOU STILL END UP HAVING TO FIGURE IT OUT FOR THE FIRST TIME. AGAIN.
Partly, this is because every puppy and every novel come with unique issues that you've never dealt with before. Issues like digging, and multiple points of view. What worked for the last puppy/novel, you finally realize, won't work for this one.
But before this comes the inevitable period of denial. The last one was so easy, you think in despair. How come this one is so hard? What am I doing wrong?
Buck up, little butterfly. You're indulging in Retrospective Canonization, in which the last puppy or novel is viewed through the fond, hazy spectacles of selective amnesia. The last book never tied you up in knots like this; it practically poured itself through your fingers onto the pages! The last puppy never had diarrhea under the dining room table; in fact, the last puppy hardly had bowel movements at all. Ever!
Forgotten are the tears shed over literary corners you kept writing yourself into. Forgotten are the wee hours of the morning when you shielded your eyes from the copyeditor's notes, moaning, I can't rewrite that damn chapter one more time, I can't, why, God, WHY? Forgotten are the decimated vegetable beds, the ruined carpets, the lunatic barking which made the neighbor complain.
Take off the spectacles. Remember it all, both fair and foul. You figured out the last one, didn't you? And it didn't turn out so badly. This one will be just as hard. But you'll get there, and you'll learn some new things along the way.
Bear in mind, though...
THERE IS ALWAYS ONE UNSOLVABLE PROBLEM.
Maybe it's the unlikely coincidence in Chapter 18 that you hate, but without which, the entire rest of the plot falls apart. Maybe it's the cat-chasing. You try everything. Nothing works. So you end up jerry-rigging. You set up something in Chapter 2 so readers believe Chapter 18 might actually happen that way. You wedge baby gates in strategic doorways to keep Puppy from careening around the house after terrified felines.
Perfect? No. But it'll have to do. Because...
YOU'RE NEVER FINISHED. AND YET, AT SOME POINT, YOU ARE.
You never completely finish writing a novel. You never completely finish training a puppy. You simply get to the point where, with whatever time and talent you have, you've done the best you can do.
At that point, with all your hard work, and a little luck, novel or puppy can then appear in public without causing you embarrassment.
Or at least...not that much.