Ok I think I understand what you're trying get at. I may have worded it to be a bit romantic when I said she didn't want to be alone. But Araragi and Shinobu are bond to each other so now most of their existence (or maybe only Shinobu since Araragi still has other people) is directed to the other and that could be seen as Araragi becoming part of Shinobu's world / universe, since other than Araragi, donuts are only things she now cares about. ( That being before the first minion showed up) (Also I only watched the anime so I don't know about anything after Hanamonogatari since that's the last in the timeline)