Wait.... NONONONONONO this looks way too final don't do this to me Hata.
Although if you stop to think about it, there's no way it's gonna end there, right? There's still the new house, the Romcoms around them... I just caught up after binge-reading this for 2 days, I don't want it to end now... I hope Hata is just trolling us because he saw the 100th chapter milestone and wanted to scare us.
EDIT: I've been thinking, and I don't think Wifey is Kaguya-hime, or at least not in the sense of the original legend. It makes no sense at all, if you think about it: in the legend, Kaguya only spends what, 20 years in the human world? She goes back to the moon and forgets everything as soon as the moonpeople put the cloak/mantle/whatever on her shoulders. Meanwhile, Tsukasa has been around for at least a thousand years and clearly remembers everything. At most, this might follow an alternate version of the legend where she either refused or couldn't go back to the moon, so she was cursed to stay in the human world forever.
All in all, I'm glad we're getting to know a bit more of her story, but I hope it just goes back to everyday fluff soon, because the more we learn about her, the closer we are to this series ending. And I am not prepared for that.