The ending

i did enjoy Joker 2 and gave it 7 on IMDB (gave 9 for the first Joker) , just disappointed by the ending , I was hoping he would be so sad because of his gf dumping him he would create a whole new movement and unleash his wrath and anger in a 3rd movie with all his followers, no big action or shooting scenes needed just the same bleak style/atmosphere slowing creeping inside your brain and heart as the first two movies.

The big question: Why did he suddenly "stopped" being the Joker? Didn't he understand that the ONLY reason the girl liked him was because he was the Joker and all the fantasy that went with it?
Was it one more way to show the viewers how delusional (or dumb ?) he was? Or the writers knew we would expect something "big" (like him escaping) so to surprise the viewers they made it that way?