You want to know the secret?
Take a look at their fan-art, their fan-fiction and what do you see? I will tell you...."not what the canon has shown." That's how they live with it. You see, in truth, they are in denial more than we are because they can't even accept the canon for what it is or their pairings. They paint NH and SS in these very romantic light, but in the canon manga and story that is not the case. Their denial is the fantasy that they live in that NH and SS is a "happy and wonderful relationship." Which is why the idea of divorce is so hurtful to them because they know any couple in real life would have been divorced by now.
Yes, Yes, I know you're completely right.
But what perplexes me the most is HOW on earth can they be all giggly about their canon?! I understand the idea of superimposing your fanon on canon, but the blatant lack of angry people (there are some, but they are so very few) howling 'hey you, yes you, kishimoto, you warped my OTP and RUINED it' is bloody baffling.
I know, River in Egypt. Still I'm certain that if something like this happened to 'our ship' (not particularly speaking of NS here, just of a OTP in a very general way) many of us - me included obvs - would be roaring pissed.
So why why why are they this happy and jolly? Could it really be only stupidity? Should I believe that all these people, just because of what they ship, are this dumb?? How could there be quite a number of qualitatively good fan fictions about SS (I won't read NH not even under torture at this point) well planned and yada yada written by people who gush at this ending and who aren't even remotely angry for what Kishicash did to their OTP??
Really, at this point my question is much more 'anthropological' than just 'Naruto-fandom'.
Sigh....no matter how much I try to think the answer still remains a mystery. 
- L'inguaribile ottimismo di un dodo.
Hungry for glory - AS Roma 1927
But they were all of them deceived, for another canon was made. In the land of Japan, in the fires of Studio Pierrot, the dark Lord Kishimoto forged in secret a master canon, to control all others, and into this canon, he poured his cruelty, his malice, and his will to dominate all life. One canon to rule them all.