Mabayu is a really interesting character because, despite initially appearing as selfish, cynical and honestly kinda pathetic, in a very normal antisocial teenage sort of a way, under the surface is really strongly defined by her feelings of guilt and lack of self worth more than anything else regarding what she does over scene 0.
Mabayu, before erasing herself at the end, dies for Homura twice, both times with no guarantee she would wake back up at the start of the month. While, for the first time, you could argue that Mabayu's magic made her do it since it showed her doing that, but that doesn't change the fact it was something she was willing to chose, it helped her save Homura successfully but only because when using that magic, her dying so Homura wouldn't was something she was willing to do. She didn't have to do that, the first time she wasn't even friends with Homura, and were she actually self interested could have just convinced Sakie to leave the city for the end of April and avoided any personal consequences at all. Since the loop would end with Homura.
She also can't bear harming people. When Sayaka accuses her of manipulating her she feels bad enough about it she basically just checks out for the rest of film. She doesn't self justify it by pointing out she was trying to save Sayaka or anything, she just kinda gives up and spends the rest of the month hating herself for that. When she learns what she had manipulated people into doing with Mami, she instantly comes to the conclusion the guilt will drive her to witchhood. Her erasing herself is partially driven by not feeling like she can cope with knowing she erased Mami's memories in film 13. Which justifies her what is effectively suicide under the reasoning it will lead to Madokami happening.
What's notable is Mabayu never really seems to strongly blame people for stuff aside from herself and maybe Kyubey eventually. She decides she practically deserves to be a witch in film 12 but never implies the same thing about Mami, despite everything they did recruiting magical girls being a team effort. She doesn't hold a grudge after Kyouko literally kills her even.
Her low self esteem also manifests in her not seeing herself as deserving of things. The moment Kyubey suggests Mabayu could take Madoka's place, she's horrified at the thought, despite her entire reason for working so hard being her admiration for Homura. When Kyouko suggests that Mabayu could use the loops to be hedonistic or that she might not want them to end, she gets so guilty she spends the rest of the day panicking about how to win this loop asap. Despite her entire goal being helping Homura, Mabayu refuses to ever purposely take any advantage of her friendship with her. Refusing to admit she might be enjoying anything about her time looping and denies the possibility of Homura holding affection towards her in any strong way other than as friendship that doesn't strongly matter compared to what Madoka is to Homura. Panicking at implications Homura might care more than that despite once again, only being there for Homura.
Anyway, she is really not ok, despite coming across as dysfunctional in a normal sort of way rather than appearing visibly depressed initially.
In conclusion, the only people capable of holding friendship with Homura are people like Mabayu or Madoka who have 0 self worth and who then sacrifice themselves for the sake of the universe. This is because Homura is never allowed to catch a break or have a successful friendship under any circumstances.
