It depends on the developpement that main character gets.
Naruto never doubt about his feelings unlike Sakura. This developpement begin normally in the beginning, not in the last 50 chapters of the story.
So yeah, in Naruto's case, as the main character, he will win Sakura's love for sure, because the author never did him doubt about his first feelings.
Yes, that's the problem. Naruto's love is not seen as a bad thing. It's much different from Sakura's love. Sakura's love is really damaged because the guy she loves isn't a great guy and makes her depressed. There's no indication from Naruto that his love is bad and makes him depressed. You want to know what's the real problem according to Naruto? The answer is him. He doesn't blame Sakura but rather look down on himself because he feels unworthy. That's not a bad thing because he can overcome it. On top of that, that's not a reason to move on, rather improve it and advance it to the next stage, where you feel happy about everything and ready to hit the goal. For Sakura, it's different because the guy is not helping his own relationship and he is never shown to be persuaded by her words. Her problem is the guy who she loves and that's not a good sign. Yes, she hasn't move on, but reality is finally clicking. Ino had her dad to reassure herself. Sakura needs to do alone unless Naruto or anyone close realizes her feelings.
Naruto and Sakura are always close to each other physically as well as communication. There's no flaws for Naruto, rather taking the blame on himself. Sakura has flaws because Sasuke is not around, didn't have a great start let alone good, and admitted that both of them really have no chemistry, only to acknowledge that Team 7 is what kept him, not her alone. She has reasons to move on and again, the great guy talk is the first click to reality check to her love life. I don't think she remembered what's considered a great love couple, and since that's being said she just now thought that's not true for her. It's slowly but surely coming around. Naruto hasn't done anything that's like confessing or very charming to her, but if one of them happens, it will hit her hard. So yeah, why Naruto has to move on is beyond me and offensive.