Gokuri

A twisted romance about a former high school student who accidentally cursed his (already taken) crush. The girl was forced to regularly swallow his semen or suffer and die, all despite having a boyfriend. Ten years after this bizarre ordeal, the high school student is now a working adult and struggling in a sexless marriage with another woman. Just as he wants to come clean with his feelings, he has an unexpected reunion. (source: Manga Mogura)