About the thing of Naruto saying that Sakura was his girlfriend in war arc
You guys know the word: running gag ? humor ? Because I think you are taking everything on first-degree. =D
Here some psycho:
First of all, naruto have a nindo of never giving up, it's one of his trademark, and nearly veryone at Konoha know that. Or we have seen several time that he gave up his love of her that much since Iron country. Out there he understood the deepness of sakura love's for emosuke ( he was emosuke during that time) If he didn't made that joke, some of his close friends would have notice that something's wrong. If the hero, the one who have done more than nearly an entire army, the one who have to deal with everything, if he showed it, then the morale could have gone bad, and morale in there is important. So admitting that he couldn't have sakura's love could have hurt him but also everyone close ( and with domino effect everyone).
Admitting it in front of everyone would show that he gave up, and naruto giving up was the last thing to see.
Se he made a joke in order to dissimulate the fact that he gave up on sakura and focues in her happiness with sasuke instead of him.
You know guys, that a lot of characters in manga and real life men hides that kind of wounds with humor ? ( City hunter for example =D)