I'm guessing the artist got told she was getting cancelled and had to wrap things up in X chapters given how abruptly the series pivoted from "their relationship is under strain and each of them is thinking the other one is better off without them" to "actually we're together and things are great, never mind." Cue a few chapters of fluff with not much going on since there's no time for another cosplay arc and we're done.
I really want at least enough chapters for one more tankabon to explore their relationship and the other characters. I'm just sad we will no longer get our monthly sugar fix...
This is quite literally one of the most successful manga the publisher has right now.
We're talking about a manga that, on a per-volume basis, sells more than titles like CSM, just to give an example:
01./ Jujutsu Kaisen - 2,870,574
02./ Dandadan - 1,894,622
03./ My Hero Academia - ~1,475,000
04./ Blue Lock - 1,119,845
05./ Blue Box - 844,554
06./ Kingdom - ~670,000
07./ [Oshi no Ko] - ~655,000
08./ Sakamoto Days - ~555,000
09./ Toilet-Bound Hanako-kun - ~545,000
10./ The Apothecary Diaries - ~490,000
11./ Haikyu!! - ~405,000
12./ Chiikawa Nanka Chiisakute Kawaii Yatsu - ~370,000
13./ One Piece - ~355,000 14./ My Dress-up Darling - ~320,000
15./ Kagurabachi - ~310,000
16./ That Time I Got Reincarnated as a Slime - ~305,000
17./ Chainsaw Man - ~290,000
18./ Medalist - ~290,000
19./ Welcome to Demon School! Iruma-kun - ~270,000
20./ Wind Breaker - ~270,000
21./ Kaiju No. 8 - ~265,000
There have been rumors for a while that the mangaka was exhausted, not just from the workload of the manga but also from the anime, and that her health had been deteriorating, especially with how she had been rushing plot points and the last break she took late last year, so this was somewhat expected... Still, it's such a shame, because it had crazy potential to develop the romance further.
I don't believe it's ending because of lack of ideas. If the author didn't have any, the editor would have. Even if she didn't know how to write a couple after they got together, she could have put the relationship in the background and kept going with the cosplay for a while longer. This isn't a case of wrapping up all the sub plots at the point of the confession because once together it's happily ever after - the end. There were plot lines being set up for later that were dropped just to end the story. Author probably doesn't want or can't continue writing so she decided to end it no matter how abruptly.
I wonder if it's because they are ending that they half-assed the uniform pants and skirt flannel pattern. Literally just applied onto the page and did a few lines to indicate wrinkles.
Every time I think I'm used to the fact that the entire fucking manga industry sucks at ending a story I get hit with one of these where I realize I was hoping for better only because of my disappointment. And it can be done. There are manga with actually satisfying endings. They're rare but they exist. I gmforget the guys name but the dude who did Lucifer and biscuit hammer and spirit circle wrote great endings. You can tell he actually had a plan going in. But then you get the ethos of pump those chapters out as long as you possibly can until you collapse and where does that get us? Right here.