Wasn't a big part of the end of Spikes ark him explicitly not getting back together with her? Like she was his lost love, but she was also very not good for him.
I'm glad time stood still for these two, it's been years since K-On! yet we are still blessed with fan arts, and this one was so lovely. I hope there's some Ritsu x Mio in future as well!!!
The fact that there isn't more Cybelle NSFW fan art is a crime against humanity, time to commission, is what I say if I did not spend money on other things.