I love the Naruto series and I will admit to being a NaruHina shipper. This isn't to say I hate Sakura or Sasuke, personally I think Sasuke should have ended up with Karin (making him and Naruto proper family, as Karin is an Uzimaki) and that Sakura should have struck out on her own - she's too badass for any male to handle.
I also L-O-V-E the Harry Potter series. Again, I'm a big Harry/Ginny, Ron/Herminone fan and a big fan of James and Lily Potter.
But alas there are fans who are upset. NaruSaku fans, NaruSasu fans, Harminone fans, Snape/Lily fans. Now, the Harry Potter fandom are pretty chill, unless you dare say the slightest thing negative about Snape, who, if you recall from the books, was just as nasty to James as James was to him. Snape also had his own posse against the Marauders. Naruto fans on the other hand...
Constructive criticism is awesome, but seriously? Sending death threats to Kishimoto? Calling Hinata names? Throwing huge temper tantrums over social media? Wow.
The fact is, as a writer myself, I know that not everyone is going to like how my story goes. But it's MY story. I can do with it whatever I like. They're my characters, I'm the one who created them and brought them to life. If you don't like what I do with them, you have a few options:
1. Stop reading.
2. Write a fanfiction detailing how YOU think it should be (seriously, this option. This is a good option. Go this option. I wanna see a Chuckles and Giggles fanfiction!).
3. Accept it and enjoy the work for what it is.
Sending death threats and getting all upset is NOT the way to go about it. People put a lot of hard work and passion into their art. They're creating their own world, and because they want to entertain people they decide to share their world with everyone else. One way to make sure that people stop sharing their work is to overreact massively when something happens that you don't like.
Be sad that Naruto didn't end up with Sakura. Be upset that Lily chose James over Snape. But no death threats. Enjoy the works for what they are, and be grateful that people are creating books, shows, movies and manga for you to enjoy in the first place!