I do wish so much that we got the same level of love and care for NaruSaku especially in the later half of Part 2 without Masashi throwing a bone to get the fandoms to wag their tails... like "OMG could it be? Could it be?" and I'm just like thinking.... as an aspiring writer..... this is not how to win over your readers when it comes to developing romance between two characters. I know the argument a lot of people make is "Well Naruto isn't a romance therefore it's fine we didn't get a lot of focus..." that has always been such a poor excuse I've heard time and time again.
If you as the writer already know from the conception of your story that this couple is going to be canon then just focus on developing that pairing as you are telling the story you've created.
That is definitely the #1 thing Masashi didn't understand when it came to Naruto.
Around 70% of the fandom was focused on power levels and the plot. Meanwhile, pairing fans were constantly discussing their parallels, pairings, getting embroiled in shipping wars and mocking rival fans on Tumblr, blowing things out of proportion.
For example, I've even encountered many NaruSaku Shippers who believe Naruto failed completely as a character because he 'lost' Sakura and moved on.
Maybe if these fans had dedicated themselves more to the actual manga plot instead of talking about ship wars and pairings all the time, the shock and rage wouldn't have been so great for the losing side. Inevitably, in a love triangle dragged out for so long, some part of the fandom will feel like losers, whether they were SS, NH, or NS fans.
Anyway, this isn't exclusive to Kishimoto or Naruto manga. Ichigo and Rukia fans were outraged that Ichigo ended up with Orihime. Even today, there are shipping wars in the Avatar fandom, with Zutara and KataAang fans insulting each other and Zutara fans refusing to accept the canon.