
But at the very least he could comprehend that they would make each other the happiest.

To reply your last post, you are right. He knows the whole ordeal of Naruto putting his life for her. It was so groundbreaking, that he has to acknowledge it for Sakura because he did it all for her. After that, he never really think of her as anything more than a family member. It was hardly if not never her in a individual slot. Naruto always sees his team as one and on their own. Sasuke probably already know it's them as together are better off since they seems to share the same likings and what not. The thing is I think Sasuke can see within themselves and probably see them more capable with each other than with Sasuke. Plus, since Naruto is soon to be admitted best friend/brother, he will support him, which may catch Naruto off-guard. Sai is already the same, so you can say Naruto is the one to receive support.
Naruto doesn't really support SS rather doing what's good to keep Sakura happy. It's not like he will push Sasuke to love her, rather just be glad that Sasuke is back and Sakura don't need to worry about Team 7 anymore. Remember, Naruto still wants to confess. If he was an SS fan, why would he even want to confess, let alone not seeing her being in love with Sasuke as a problem but put the blame on him? Oddly it may sound to draw a comparison, but it could go similar to Berserk, er, the first part because Guts at one scene pushed Casca to Griffith. Then, well, the usual main characters prevail in terms of love interest. But that's only in one arc, but yeah, it's a long story. My point is people can change overtime and/or only show one fun support, only for you to win the love. So in Naruto's world, let's say Sasuke is finally back. Naruto push Sakura to Sasuke. Fans cry, blah blah blah. Give in a few chapters more, oh crap, NS is canon. Hm, Naruto seems like a watered down Berserk (a big one), but that's not to bash Naruto, because it's a different altogether. I'm just saying following the flashback arc, two best friends happen only for that best friend to become the main antagonist. Hm...
Well, I hope this reply do any good for you.