Homura would be miserable after saving Madoka.
(This is more of an imaginative exercise than an interpretation that I want people to accept) Homura, after each timeline, becomes increasingly distant and different from the Homura for whom Madoka unhesitatingly sacrificed her own friend (Mami) to save. To be blunt, if Homura hadn't managed to kill Walpurginatch in the anime's timeline, her next big challenge would have been to build a relationship with Madoka. But this would frustrate her, because she would soon realize that the Homura Madoka liked was quite different from the Homura she is now. Most likely, Madoka wouldn't become as close and friendly with Homura after all these events; they would be friends, but distant friends who share a trauma, They wouldn't be best friends or even lovers anymore.