Well, I wouldn't say that's true. While there's no getting around the fact that Sakura thought of Sasuke when the Lover-nin was talking about love in #540, due to slight variations in the translations I don't think it's 100% clear what's going on.
First of all, it's interesting to note that the most significant thing Sakura actually says ("There's someone else I...") is in #539 -- purposely separated from the rest of the scene by a week's time. I didn't use to think that mattered and have argued the opposite out here before, but I've changed my mind since the release of the official English Jump volume. In that version she says, "I have someone already, though, you see..."
I am now more inclined to think that Kishimoto broke the scene that way because the guy Sakura is talking about in #539 -- the "someone" -- is Naruto. I mean, think about it. When the Lover-nin scene happened Sakura already recognized that Sasuke was no longer the same person she had loved. She knew he had nearly murdered Karin. She had already tried to kill Sasuke twice and he had tried to kill her twice, and she had already more or less made a commitment to Naruto in front of witnesses.
Even in the worst case -- if Sakura was flat out lying to Naruto during her confession and she has no feelings for him at all -- in #539-540 she still knew perfectly well that she does not "have" Sasuke, and he is not someone she can in any way count as a person in her life. It makes no sense that she was referring to Sasuke as the "someone else."
As for what Lover-nin says in #540:
"But there is one thing that I know... If it's somebody that you like, then they're bound to be a great person!" (Mangareader)
"Hope it works out for you. He must be a really great guy if you're in love with him." (Mangastream)
"Well, good luck. If you love him he must be a good man." (English Jump, vol. 57)
When Sakura then thinks of Sasuke, can we be 100% sure why? Was it meant to reflect her disappointment in herself because she still loves him? Or meant to reflect her disappointment that she ever loved him?
Although Naruto was not shown as the positive replacement in the same panel, I still think it can be reasonably argued that Sakura's disappointment was mainly about having ever loved Sasuke. It is consistent with her reaction to Sai's revelation -- that her feelings for Sasuke are a source of great pain to Naruto, a guy she knows is a "good man."
Something to consider, anyway.
Beyond that we have other, more recent evidence that Sakura's feelings for Sasuke have changed. When Sasuke appeared on the battlefield she showed wide-eyed surprise at his arrival to "help," but later a huge panel was dedicated to the implication that she does not trust him. Likewise, when Team 7 reunited to fight the enemy, Sakura spoke only to Naruto. It was as if Sasuke was not relevant.
And all of that was on top of the fact that she did not deny Naruto's assertion to his father that they were boyfriend/girlfriend in #631. So yeah. I think Kishimoto has been moving Sakura beyond Sasuke -- slowly, maybe, but surely.
ETA: By saying that during the reunion Sakura only spoke to Naruto, I meant when she was claiming her right to fight with them.
But it frustrates me when people think that "the inside counts" only applies when the person isn't pretty on the outside.
But it's just what I think, I think it's been hinted at but there's no proof. Then there's that I personally think she is super-pretty.
They said that he only likes her for her looks. Nevermind that later in that same chapter we got a (not shallow) reason he likes her, and we never get a reason that Sakura loves Naruto. 
That really pissed me off, not gonna lie.
