God damn this was a rollercoaster of a chapter. TBH I expected something like this to happen though, the MC has basically been addicted (idk if that is the right word to use in this context, but whatever) to his sister for what appears to be a LONG time so his desires run DEEP. Matsuri won't be able to get rid of those desires or replace his sister as the object of those desires that easily, this "relationship" was bound to fall apart the second MC realizes that he can't imagine being with anyone besides her, so F in chat for Matsuri. (It also didn't help that Shizuku is basically a Yandere that is manipulating MC and conditioning him from the start so...)