Throughout Naruto and a lot of Naruto Shippuden you can clearly see that Naruto has a lot of affection towards Sakura. Various times he tries to ask her out and the like but it never goes very well for him. We do eventually learn later in "Naruto:the Last" that Naruto's feelings for Sakura were another way for him to compete with Sasuke, but his feelings cannot be simply denied.
My question is: has Sakura ever shown signs of love, not friendship, towards Naruto throughout the series? When?
I don't agree with the answer above or any answer on the Internet for that matter. I watched Naruto Shippuden dubbed and subbed and to my understanding, Sakura did develop feelings for Naruto (and people usually skip those episodes because they are fillers).
After defeating Pain, Sakura recalls her days with Naruto (not Sasuke) and realizes that she has developed feelings for him. Later (in canon episodes), she decides to get rid of Sasuke herself because she felt responsible for it somehow. Sometimes, fillers are made to tune the main story and you should not skip these fillers if you like watching this show.
Every answer I saw described the situation poorly, so I decided to pen down the real story, in my belief.
Sakura did like Naruto, but the problem is that she was not mature enough and believed herself "deserving" for Naruto, as he was a hero, unlike Sasuke. She risked sabotaging Naruto and Hinata's story for her reasons. On the plus side, Naruto knew Sakura was not meant for her so he downright says her "No" on episode 206 (Sakura's feelings).
Later in series, she realized her "true" feelings towards Sasuke as he helped Naruto defeating Kaguya and got what she deserved (abandoned and knocked by her dear loverboy, whose thorns she desperately needed for 6 years)
I rewatched the entire Shippuden again, and my new conclusions somehow contradict this (my old answer). So here it is:
Sakura loves Naruto, but only platonic. She shares sympathy with him and they are good friends. She cares about him and that's why she confessed her love.
There are two side-effects in the cannon because of this:
1. Naruto realizes that Sakura can never be together with him (the same episode Sakura proposes to Naruto). He realizes that he actually never loved Sakura himself. And that was the moment he knew Sakura and Sasuke belongs together. Writer stitches the story beautifully there. And because of this, his self-righteous self forces him to sacrifice himself to bring back Sasuke. He just couldn't let Sakura suffer anymore. As he owes that to Sasuke.
2. Sakura gained some real heat after this scene from fans, as she seemed to neglect Hinata. But for me, this scene was pure satisfaction, her being rejected by our hero.
Sakura belonged to Sasuke. Naruto knew this. That was a pivoting moment of the plot. If Sakura had never confessed her love, Naruto probably went for a kill in the fight followed that episode. And we know he could easily swamp Sasuke as he was tired from the Danzo fight. But again, probably Obito intervened earlier, but in any case, the story would turn differently. So yeah, Sakura loved Naruto. But not as much as she loved Sasuke. She had undying respect for the former.