I don't know how to feel about the ending? It feels calm and peaceful, we get to see them thrive in the lives they chose for themselves and support each other as they do so. What a nice little bond they made for each other!
That said this just felt like... well nothing happened. A year went by and nothing unexpected happened? Kasane is having fun at her job, Subaru is still going to events with Masamune and that's it. I'm not saying this had to end with marriage and kids or anything but... you could have just not published this and it's how I would assume stuff went by just extending the status quo forwards in time.
Shit I would have taken like a goodbye butt slap to Subaru as a sign that their relationship is much more relaxed now and Kasane is more comfortable (also callback to chapter 1) but okay. I still love this series, hopefully the authors next work can be a bit longer.