Even if I think it would've been great at triple this length, I also think it ended perfectly for what this set out to be.
They're together, they're happy, and Karin's finding her way and has accepted both Yuu's love for her, her love for him, and it would seem also herself.
And I like the last little sendoff - the more sides of you there are, the more you can share with That Person, and the more of you That Person gets to cherish.
Thanks for your time and care on this series. An unexpected gem out of the last year or so of manga.