Barefoot in the Park (1967), directed by Gene Saks.
Newlywed Robert Redford is lucky in that he has Jane Fonda for a sexually voracious bride. He is less lucky in that she is a childish "free spirit" whose main entertainment is embarrassing him in public. She seems to have no idea that he has to work. Ever. Guess what? They fight. They make up again after he becomes a sick drunken bum. That's entertainment.
Well, it's not all dismal. Fixing up the mom (Mildred Natwick) with the eccentric neighbor (Charles Boyer) is a nice bit. Fonda's short skirts and pajama tops are prominently featured.
This was during that long period when Broadway and Hollywood's mission was to shock the button-downed normal stiffs out of their conformist complacency and make them celebrate the alternative and bohemian.
I've never watched a Neil Simon film or play that I wanted to see again. It's weak comedy. The bit with the five flights of stairs: once or twice would have been enough, yes?