"agree...it's probably the draggiest part of the whole film. But it showed the main protagonist as especially warm and caring, so I guess it worked for that reason."
The reason for the subplot was to make Teresa likeable and sympathetic. If she was depicted the way she was in the book, the movie goers would probably have yelled at the screen "hurry up and get killed already!" The Teresa in the novel was, as one critic put it, "a chilly, unpleasant woman." But she was very caring towards her students. She mused about her Jekyll and Hyde life; by day she's Teresa, a sweet, kind teacher of little children, by night she's Terry, who "whored around in bars."
"IIRC, Rossner wrote her book after another writer wrote a book based on the same murder; however, the 1st writer was slammed for portraying Theresa as, yes, a slut. Rossner's version was meant to be sympathetic to Theresa and why she might have ended up as she did.
Anyone else remember this?"
Actually Rossner's book came out first, in 1975. In 1977 a journalist named Lacey Fosburgh came out with "Closing Time: the true story of the Goodbar murder." It's not a very good book. She doesn't even use the real names of the two principles! In "Closing Time" Roseann Quinn is "Katherine Cleary" and John Wayne Wilson is "Joe Willie Simpson."
Wilson's family cooperated fully with Fosburgh, so there's a lot of info on him, none of it interesting. He was just a dumb, not very intelligent clunk.
Quinn's family and friends would not speak about her at all after her death, so Fosburgh has to dig up what she can about her, and none of it is much good. Fosburgh's take on Quinn is that she had a lot of self hatred primarily due to being crippled by scoliosis, maybe even a death wish. She was a lonely, emotionally cut-off woman. As for her being portrayed as a "slut"...well, it didn't seem that way to me. She picked up guys in bars, but then that was what lots of people did back then, It wasn't considered any big deal.
Fosburgh stupidly recreates the conversation she imagines Quinn and Wilson might have had in the bar before they head off to her place. Why make stuff up? It's supposed to be a NONFICTION account of an actual crime. Considering the lack of information she had on Quinn, I guess she was trying to fill the book out in whatever way she could.
Anyway, here's a short review of "Closing Time":
"Well, almost the true story--names have been altered and Fosburgh, who covered the original murder for the New York Times, has added some not very convincing street-wise dialogue. Her point seems to be the existential absurdity of it all: the chance events that led Joe Willie Simpson, a quiet farm boy turned drifter, to meet the lonely Catholic schoolteacher in the kind of bar that's designed for just such purposes. . . . What Fosburgh does is to reconstruct the lives of the murderer and the victim in such a way that the withdrawn, emotionless Joe Willie becomes as much to be pitied as Katherine Cleary, the girl he stabbed eighteen times. (The throw-away-the-key and execution-is-too-good-for-'em crowd will hate it.) Only too late would Joe Willie be tagged as a schizophrenic-- after, that is, he had knotted some sheets together and hung himself in the Tombs. The prosecutor took the words right out of Fosburgh's mouth: ""He reminded me of L'Etranger and Camus' existential hero. He was like Mersault, the guy who killed his mother. He had no feelings, no remorse. He didn't care about anything."" And back home in Illinois, where Joe Willie's ""American Gothic"" family lived, his mother just couldn't take ""anything more bad said about him in the newspapers""--because she knew in her heart that ""He's a good boy, a real fine boy."" None of these tragic facts were understood by the press or by a public baying for revenge. But for the Mr. Goodbar audience, neither Joe Willie nor Katherine Cleary has enough emotional ballast to score the second time around."