Alright, I'm going to go on a short, spoiler-tagged rant about Homura here, because I love her and I want her and Madoka to be happy together.
Spoiler:
First off, if it weren't for that final part of Rebellion, where Homura explicitly goes against Madoka's wishes, their relationship wouldn't be considered abusive. Yes, in the main series, Homura was acting selfishly selfless, in that she was willing to let everyone else die if only to prevent Madoka from harm, but in the end of the series, Homura cares about Madoka, and wants her to be happy. I can see where the ending of Rebellion comes from, but it seems a little bit out of character for Homura. That aside, their relationship at the end of Rebellion is definitely abusive.
It's not out of character at all, though.
You can say that TV anime Homura was working in Madoka's best interest and wanted her to be happy, but do you see much of Madoka being happy at all in the series? Especially when Homura's around? No, and this is because Homura is always working for Madoka's best interest and happiness on
her terms, not Madoka's. A huge thing about Madoka's character is that she wants to help people at all costs. Kyouko even calls Madoka out on this because making a wish on a whim like that is very foolish. However,
she still leaves the choice up to her. Homura, on the other hand, does everything she possibly can to keep Madoka under her terms of 'safe and happy'-- but in Madoka's eyes, more than anything, she just feels worthless and powerless. Homura took Madoka's agency away, making her feel as if she can't help anyone, and has to watch her best friend and new senpai get killed right before her eyes-- all the while knowing that if she were able to contract, she could have helped them! So add guilt on top of all of that, and Homura's utter obliviousness to this, because she doesn't care about Madoka being happy on her own terms-- especially if those terms don't involve her. Madoka contracting and sacrificing her human life to not only save everyone from Walpurgisnacht, but also retroactively save all magical girls and change the system they were currently in. And she was happy about that. Even if it's not what Homura wanted.
If anyone is up to reading a wall of text analysis of Homura and her actions on Rebellion, I think this one is absolutely spot-on.
I'm glad you liked it. I've definitely had some mixed responses on that analysis ranging from agreement to alternative ideas and valid counterpoints to frothing rage.