I've been thinking on how Kishi writes romantic love in this series and the major differences between Sakura's, Hinata's, Karin's vs. Lee's and Naruto's "crushes". I don't believe Kishi writes things like this the right way and that all of these character's romantic interests, in some way or another, have a major issue with them. This is my analysis on it, particularly of Naruto's feelings later, and I'd like to see what you guys think. :)
First of all, there's Sakura, Hinata, and Karin. Starting with Hinata, she fell in love with Naruto so much to point she'd kill herself pointlessly to protect him, yet she's barely interacted with him this whole series. But every time we see her, we get her feelings shoved in our faces without any realistic basis. She doesn't know him that well and we usually mostly see her admiring him, yet she still pursues him and insists she loves him.
Next, Sakura with Sasuke. She fell for him very deeply but once again her love has no real basis either. Sasuke never acknowledged her and treated her with indifference most of the time. They've never interacted meaningfully and even though they were together more than Naruto & Hinata, he still never really opened up to her or did much for her as a real friend. Yet, Sakura made this unrealistically powerful love confession and gets heartbroken by Sasuke well after he leaves and even now a little bit. She "loves/loved" him and we're just supposed to take it without any real reason to.
And Karin ... I'll state my honest opinion. I apologize if it offends any SK shippers here. Her love feels shallow. We see Karin fangirling Sasuke's coolness, his looks, and a sexual appetite for him to point she nearly rapes him while unconscious. It feels very shallow and overly exaggerated comic relief until the Kage Summit Arc and 662, but the fact is we only ever saw all shallow feelings for Sasuke beforehand. How are we supposed to believe she loves him under circumstances like that? If a pairing's too much comic relief, then you can't take it seriously. Why does Karin really love him? Saying she likes his smile still feels shallow and if it's because he saved her, then that's hero worship. If it's going to stick around, I'd rather see her feelings treated a little more seriously (I don't know, like loving his personality) than overly exaggerated comic relief.
Most of the main Naruto girls focus is who they love while the boys who have romantic interests don't think about this even half as much. Even Lee, who people often compare to Hinata, is more likable and developed because he's not just his love for Sakura. He also wants to be a worthy ninja and make his teacher proud, rarely thinking about Sakura. Yet, for some reason, the girls focus more on love when they should be as well-rounded as them. It feels like an unfairly uneven scale. They should have more important bonds with more people and more focus on other goals instead of being with who they love or, in Sakura's case, figuring who they love.
Sakura is slightly different because she does have her own goals (she's the best developed female character in the series for sure), but she's not entirely free from this either. If I'm completely honest, most of Sakura's character is entirely taken up by her relationships with Naruto and Sasuke. She focuses more on them while her other goals/even relationships get sidelined in relevancy. Her bond with Tsunade isn't highlighted much and even her rivalry with Ino, that had a lot of potential, might as well not even exist in Part 2. Sakura's main bonds being her love relationships with Naruto and Sasuke isn't exactly a problem, but it is focused on too much. Naruto's the positive influence, but that doesn't mean Kishi can't be a little more flexible and give more focus to other bonds instead of just Naruto, Sasuke, and then more Naruto by Part 2.
Sakura's not pairing fodder like Hinata and Karin, but he still does make her revolve too much around love. Other goals and relationships are important as well, you know.
And now Naruto. Unlike with Sakura and Hinata, Kishimoto actually did well giving Naruto's love for Sakura basis and development. It wasn't instantly love and developed over the course of the series. Naruto spent time with her, most of which was positive and not constantly comedic like Karin's feelings, giving his love for her more realism. It's easier to swallow than Hinata's love for Naruto or Sakura's love for Sasuke, contrary to what the rival fans/Sakura haters say.
However, there is one thing Kishimoto screwed up here and that's relevancy. Unlike Sakura, Hinata, and Karin, who are too love-oriented, Naruto's not love-oriented enough. I don't mean he has to constantly think about Sakura, like I said it's very important he has other goals and interests of his own, but he's so caught up in those it's easy to forget sometimes he actually loves her.
A SS/NH once told me Naruto's feelings aren't focused enough to be taken seriously and that they should be more like Sakura and Hinata (which I heavily disagree with, being that love-oriented is bad). But I do agree Naruto's feelings for Sakura should have a little more focus not because it's not genuine, but just so it flows right.
What I mean is Sakura's not often treated as special to Naruto. It's put on the same level of Team 7 in general and isn't often singled out as being particularly important to him the way Jiraiya, Gaara, Sasuke, and his parents are. In fact, more than any of those, she is extremely overshadowed by Sasuke who he always singles out; Sakura gets left in the cold. If he's meant to be in love with her, shouldn't she be singled out more than she is? His bond with Sasuke overshadows everything, even when Sakura's likely the girl he's going to marry and have children with someday. Now does that feel right to you? 
Has anyone ever read the Percy Jackson Series? Percy had to travel through the River Styx that could potentially kill him and he had to think of one thing to cling on to to survive. And guess what that "one thing" was? Annabeth, the girl he loved. Not his best friend Grover, not his parents, not his half-brother, just her. It gave Annabeth status as the most important person in his life or at the very least singles her out and the depth of how much he loves her is shown and believable. It's not overshadowed or even clumped together with a bunch of other people.
Now try picturing that with NaruSaku. Can you honestly see it? As much as I believe NaruSaku will be canon, I can't. It feels too out of place. I see Naruto thinking of Sasuke alone or at least Sakura thrown together with all his other friends. She's once again gets no special treatment at all when she's supposed to be the woman he loves.
Now does that scenario with Percabeth have to happen to Naruto? No. But it's still weird and badly written that Sakura's not one of his most important bonds when it comes to Sasuke or is at least put on the same scale as him. Naruto loves her. She shouldn't be shoved with the rest of his friends like she's not anything special. And I'm not even saying this as NaruSaku fan. I'm saying this as a writer in general.
I'm not saying Naruto doesn't love Sakura. I'm not saying any of the characters don't love someone any less. I just think Kishimoto could do a lot better portraying them when it comes to focus. He has no balance in his writing. A few characters either focus on their love too much and then some more characters focus on their love too little. It's because of this I truly believe Kishi when he says he's not that good at writing romance.
I hope I don't sound overly critical here. Kishimoto does have strong suits in his writing, but I have to say incorporating romance in characters is certainly not one of them.
