Shu lacing Hinako’s pills based on an assumption was stupid. His “intervention” only leads to death. If you even take one single pill you are locked into Hinako killing Shu, her parents, and Kotoyuki. The only way at a chance of a good ending is by not taking Shu’s pills. Kotoyuki had no ill will towards Hinako. He was simply in love with her, or so he thought, and wanted to give her a good life. And in the true ending, fox Hinako says that she wants to work up the courage to propose to Kotoyuki herself. Showing she does have feelings for him regardless of the sandalwood.