It ended as it should have.
But the series leaved a lot underbaked.
Aria got to step one in the romance nad never progressed from there.
Nonoka finished her first arc and was just fluff the rest of the Series.
Marina just became a gag character.
Actually only Teacher and Lylisa actually finished their characters.
Like we still dont know a lot about Okarun trauma.
We know the full extent of Okumura's trauma. His mom left his family after cheating on the dad and his family couldn't recover. His dad is a wreck and his sister was pushing Okumura away as she lashed out. Ashford Chronicles was his coping mechanism and his bond with Marina was his last connection to the 3D that got violently broken and taken away. With the subsequent bullying he retreated into Ashford Chronicles and later Lilliel Side Story as his distrust in girls and love solidified. The trauma of being capable of "loving" is what haunts him throughout the series. His fear that he would do a repeat of his mom, that he'll inevitably hurt the one he "loves" because he doesn't really love them. At least with Lilliel she's the safe option because she's an angel in heaven. The fear of being capable of loving another, loving more than Lilliel was holding him back to the very end. When he finally realized how much Mikari really meant to him and when Mikari confesses to him, that's when the phantom of his mom is erased.
Marina's the one who catches on about the nature of his trauma being related to the past. And its pushing past that and looking to the present and the future that is her main role in the story. It's why she gets that moment with him in the second training arc. If one consider's her ranking prior to Okumura's relationship development, she'd easily be top tier. But she's neither the one who blurs that 2.5 dimensional gap, nor the support in the years since she left. Its why she gave that choice at the end of her confession.
Aria, Nonoa, and Tsubaki finished their character arcs almost immediately. Aria got the full summer comiket to solidify her beliefs and growth. Romance wise she never really stood a chance, but the crush and feelings still remain. Okumura's a solid catch after all. But she's got a big enough personality to move on. Nonoa finished in Summer Comiket as well with her scene with Lilysa. And Tsubaki got her final moments when she made her cosplay for the other Summer Comiket. For the focus characters of arcs they got their own little resolutions.
The one actual loose ends would be Xiaoyou and Luluna, but the former is a victim of summer comiket taking too long, and the later because she's too much a "protagonist of another story" to get too much out of her.