Anime fans will often feel upset when teased potential couples never get together by the end of a movie or series. It happens in other entertainment media. However, it's particularly prevalent in the anime medium. This is especially true for potential couples whose romance is teased throughout the medium’s runtime; if the fans’ patience isn’t rewarded with some solid form of on-screen romance (a confession, a proposal, a kiss, a date, marriage, children, etc.), it will be as though they wasted their time. However, some manga can deliver a satisfactory ending where a romance is teased but never fulfilled. For example, Dr. Stone teased fans with the prospect of Senku Ishigami and Kohaku becoming a couple. Since neither of them was interested in such a relationship, only the hardcore shippers were upset that the series ended without these two confirming any feelings of love for each other.
Source：https://www.cbr.com/dr-stone-senku-x-kohaku-canon-chances/
