I'm not sure if Children of Eden is a bad ending or just a bad book that falls apart in Act 2. I have never read Pygmalion by Shaw and was always puzzled at Freddy's inclusion in My Fair Lady. Thanks for the tidbit!
What's the worst ending ever?
I could say Jekkyl and Hyde because it just refused to end.
Mimi living at the end of Rent certainly diminished it's impact, that's especially so the longer it runs.
I would have to say Dance of the Vampires. The Thriller-esque dance number telling us that the Vampires were not defeated and were a'comin' for us literally made me slap my forehead... oh if I spoiled the ending for you, I profusely apologize, but I doubt it's gonna have much of a regional life, so your chances of seeing it are bootlegs or Lincoln Center. Hard to believe a show like that is in a library....
I wish the stage were as narrow as the wire of a tightrope dancer, so that no incompetent would dare step upon it. -Johann Wolfgang Von Goethe