Joe has recovered from his relapse with the help of his A.A. friend Jim - what's more, he has managed to stay off the bottle for a year, commendable but spoiled by Kirsten's lack of interest in sobering up with him. She leaves her home, her husband and her daughter then bounces from one bum to another before suddenly turning up unannounced to see him.
Then ... She walks up a steep street towards Joe's rented rooms in the imposing Victorian on the right.
... in the early 1960s ... CitySleuth searched high and low in San Francisco before finally nailing this place - it was filmed in Bunker Hill, Los Angeles! The Victorian is no longer there but this vintage photo, taken about the time the movie was filmed, shows it as it was, the Chaspeak Apartments at 512 W. 2nd Street on the block between Olive (seen crossing behind Kirsten, above) and Grand Avenue (map).
In a heartrending scene Kirsten implores Joe to let her return home but he won't unless she commits to give up drinking. Unable to bring herself to do it she turns and leaves.
Then ... As she walks down the street we can just make out some kind of railing spanning 2nd Street beyond Olive.
... in 1948 ... the daytime view in this vintage image reveals the railing to be the balustrade above the 2nd Street tunnel. The building at right, the one with the 'BAR' sign on it, above, was in real life the Mission Apartments at 504 W. 2nd. (Ten years earlier this same junction was the site of the concluding scene in the movie Sudden Fear).
... and Now, the Bunker Hill neighborhood was razed in the 1950s to clear the way for a huge Civic Redevelopment project; consequently the same view now is unrecognizable. The tunnel is still there but this section of 2nd Street has been rerouted around it.
It's a sad ending as Joe watches his wife go. He has turned her away so that, for his sake and their daughter's, he will have a chance to remain sober. We can only speculate as to whether they will ever see each other again.