Why can't we all get along?
I don't know in the slightest.
Harmonians are sadly still alive, even after Half-Blood Prince their claim is that Harry was broken up with Ginny at the end of The White Tomb, and Ron and Hermione were technically not together. Most assume that they will be, but those are the sane(ish) ones.
So the bad ship Harmony still insists on sailing with a hole in the bottom and a ripped sail. Figures, they are delusional.