Singleton Larry Hubbard, who's previous girlfriend had done the dirty, has such difficulties with single life and the ritual of courtship that he writes a book about it...which becomes a best seller.
Wrong script, wrong director. Clearly desiring a change of gear, Martin took this role as an ordinary guy in a long-term relationship who's like a fish out of water when his girlfriend suddenly ups and leaves him. He stumbles upon a secret singles subculture of Lonely Guys, striking up a close relationship with the endlessly pessimistic (and typecast) Charles Grodin, and starts talking to his plants.
No riot to begin with, it's fatally wounded by the choice of director with Arthur Hiller far too sentimentally inclined to work any magic with Neil Simon's bittersweet script adaptation.
Wildly uneven, but funny in a bittersweet tittery sort of way in places.