This is a wonderful explanatory fic for HBP. When I read that book, the statement that Harry made about how it seemed to be somebody else's life, that really struck me, and right there and then I thought, "CLUE!" Coz as we all know, JKR sprinkled clues all over her books. So I'm so glad you touch upon that piece of gem in this story. Let's see how it ties in to Book 7.
Also, I don't believe JKR has completely sunk HHr ship yet. The reason is she has only commented on her work up to Book 6 (HBP). So what she has said is true up to Book 6 only. Book 7 is still wide open for anything.
Plus, by the end of Book 6, Harry did not make any commitment to seek out Ginny and pick up with her later if he succeeded in his quest.
And Hermione and Ron's relationship wasn't defined properly as boyfriend/girlfriend relationship even until the end of Book 6. Okay, so Ron comforted her during Dumbledore's funeral. But I think in grief you'll find comfort in your closest friends; that doesn't make them your boyfriend. In fact, if Harry were not busy comforting Ginny, maybe Hermione would be going to Harry for comfort. But since Ron's the only other best friend available at that grieving time, so she goes to him, and I would think, Ron needs comforting too.
I think there's another possibility for why JKR didn't make Harry promise anything to Ginny, and why JKR may be pushing R/Hr a little too much down our throat: JKR may be setting up for Harry to die in Book 7.
If that comes to pass, and Hermione and Ron both survived, maybe they will end up together. And no ship would be needed for Harry.
Another clue: Ginny's pet name, Arnold. Did JKR get that from the infamous traitor Benedict Arnold? Is Ginny going to turn out a traitor to Harry?
There's some essays that equate Harry/Ron/Hermione/Ginny to the Marauders, James/Sirius/Lupin/Pettigrew. Pettigrew wasn't really part of the trio, just a tag-along, and in the end he was the traitor. Ginny wasn't really part of the H/R/Hr trio, too. Is JKR going to make Ginny a traitor? Plus, Crookshanks keeps following Ginny, looking up at Arnold. Remember how Crookshanks behaved with Scabbers? But he doesn't behave that way with Pig or Hedwig.
Sorry, just get very enthusiastic about your fiction. It gets me thinking. Your writing is very believable.
Another reason for Hermione's OOC in Book 6, I think, is due to years of repressed frustration at Harry not noticing/liking/fancying her. He kept going off-tangent towards other girls, and maybe Hermione's getting tired of having to play a charade of being happy for him with another girl. And I think Hermione took out her frustration on Ron, since she wouldn't take it out on Harry, the one she fancies. Unfortunately, everyone misread her action to mean she likes Ron. And I think even Harry misread her.
I think Harry does like Hermione, but he thinks Ron likes her, so Harry being Harry, just doesn't allow himself to even start thinking of Hermione as a potential girlfriend. Because if the ground is too sacred for him to even venture into; if he did, and it doesn't work out, he'll not survive; so unconsciously he tells himself, don't go there at all. This is my opinion, based on some real-life observations.
And you talk about how your crush on someone turned you into someone you were not; well, been there, done that, too. In my case, I was in a relationship for 9 years with someone whom I loved hopelessly but was completely wrong for me. I turned myself inside out trying to change myself for him. It only ended up in major heartache. But yeah, I understand when you said we could become OOC because of crush or foolish love.
Last note: I'm glad you used Hermione's full name, Hermione. Harry always called her Hermione. I don't like the shortened version, Mione, that's often used in fiction. It reminds me of mayonnaise. Not cute at all. 'Hermione' is unique; and our HP's Hermione is definitely one of a kind. So I like her full name used; it is her.
Good work.