Howdy! I'm Flowey, Flowey the flower!
Anyways, I'm gonna ramble now. Introduction segment done.
So, Homura right? Homuhomu, Homegirl herself. She's a deeply broken girl.
I'm gonna talk about what I believe to be some of the why's, beyond just the looping itself.
Now, other than Madoka (A topic for an entirely different rant, honestly) and maybe Oriko (I mean, *gestures vaguely* look at the bitch, she's good at her job (Traumatizing Homosexuals)) I'd say a certain girl has hurt Homura more than anyone else.
Miki Sayaka. (Though you could argue Mami too) Now some might think this has to do with the general fragility of her mental state, but her witching out isn't what I'd say is the focus. It's the distrust.
Sayaka, despite how i usually see it passed over, was in the end one of Homura's first friends (Excluding maybe one or two people from before her surgery, but we haven't seen much implying Homu ever had friends before Madoka picked her up like a stray cat). Sayaka was, and is, someone who's opinion Homura values quite a bit, and her opinion of Homu herself hasn't exactly been good through much of the loops.
And here, I'd like to argue that this is a rather core hurt, part of turning Homura into who and what she is now. That rejection from someone who she knew as among the first to accept her, from one of her first friends.
Imagine, for a moment, the pain each time she was called evil, a monster, by that upbeat girl who was so strong and so brave. The girl that, if you ask me, looking back at Homu with the golfclub, she tried to model herself after.
It really is something I've seen quite a few fics forget, that Homura and Sayaka were friends in the beginning, that in the mind of the broken girl who doomed herself to never grow up they still are. (Sidenote : I've considered writing a snippet of Homura and Sayaka set in the Homurinth, or maybe in that world she made after her apotheosis, have them talk and have Sayaka mention that she came with in part to apologise, for all the hurtful words she'd spoken.)
Miki Sayaka is a brave, headstrong yet fragile girl, one that you can't help but admire, and I believe that Akemi Homura was swept up in that wave too. That, though they've both respectively forgotten and repressed the fact, Sayaka was an idol in the mind of that lost, lonely girl, a Hero amongst those who saved her. And perhaps that, too, is why Homura despises Sayaka's ambition to be such.