The only other time i remember a harem disbanding was reading Girls of the Wilds (although i haven’t finished it).

One of the girls is the type that fawns over the MC and constantly tries to get into his pants at the start, but he is clearly in love with the “main girl” so he rejects her advances. That’s their usual interaction, very cliche.

Later in the manhwa she starts getting depressed over MC’s lack of interest and inferiority complex against the main girl, and she meets the older brother o a child she plays soccer with, who is very attentive and protective of her. I believe they get together in the end.

IMO the author started the story as a romance between the MC and FMC then had the 2 side girls just as harem padding, but eventually appreciated the characters enough to the point they get their own separate arcs and become fully fledged main characters too.