What ever the reason it will likely
She said it before they fell. And don't let this shit get to you this author thinks they are writing something deep they aren't. Ps I am watching secret class implode right now and have been following it since chapter 1 do not make my same 5 year mistakeGoing back to chapter 28 Shizuku was crying and saying "When i thought about not being able to see Riku anymore, it made me sad", she also said "i probably won't be here next year" and then after that she said "i want to etch Riku's shape into my memory while i still can". All signs point to her moving away in my opinion, either with her parents or with Takt(she could still be having an arranged marriage with him, i insist on this because it's the only explanation i can come up with for her to even be dating him in the first place). The worst part is that this author will drag this story out for like 100+ chapters and only by then we'll be able to know what the secret is.