Not sure why there seems to be surprise here for the darker bits—the anthology title is literally Koi ni Wazurai (Agony for Love), and all the stories are about dealing with the vexations of falling in love, from love stories that came to be or those that came undone. I like it when authors have range and free reins to explore things like this.
That said, Missing Rink definitely is a weaker entry compared to Love Wars or Scandal. The Shuri side just felt pretty shoehorned for such a build-up on Rina's side of things, and the entire thing felt rushed overall.
My favorite entry has got to be Love Wars. It left a strong impression, and the buildup was nicely paced to a sweet payoff.
Thanks for the anthology!