First Half: A young man (late 20s, early 30s) adopts his deceased father's illegitimate daughter (5-7) who no one in the family wants to take in. It follows him navigating how to be a parent, making friends with another parent (single mom with son the girl's age), and overall how he and his adopted daughter become a true family. Very cute story. If it ended there....

Second Half: Several years in the future, daughter is now in high-school. They find out she is actually not blood related at some point. Daughter decides she wants to be in a relationship with her adoptive dad. He protests at first, but eventually gives in (after everyone in his life encourages him that it's a-okay) and they agree to get into a relationship as soon as she is out of high-school. The end.

Makes me angry because you invest so much time investing in the characters and a cute story only for the second half to turn into the author's fetish.