Here's most of that scene from my ebook version:
“The two of them didn’t even stop jitterbugging during the intervals. I felt myself shrinking to a small black dot against all those red and white rugs and that pine paneling. I felt like a hole in the ground. There is something demoralizing about watching two people get more and more crazy about each other, especially when you are the only extra person in the room. It’s like watching Paris from an express caboose heading in the opposite direction—every second the city gets smaller and smaller, only you feel it’s really you getting smaller and smaller and lonelier and lonelier, rushing away from all those lights and that excitement at about a million miles an hour.
Every so often Lenny and Doreen would bang into each other and kiss and then swing back to take a long drink and close in on each other again. I thought I might just lie down on the bearskin and go to sleep until Doreen felt ready to go back to the hotel. Then Lenny gave a terrible roar. I sat up. Doreen was hanging on to Lenny’s left earlobe with her teeth. “Leggo, you bitch!” Lenny stooped, and Doreen went flying up on to his shoulder, and her glass sailed out of her hand in a long, wide arc and fetched up against the pine paneling with a silly tinkle. Lenny was still roaring and whirling round so fast I couldn’t see Doreen’s face. I noticed, in the routine way you notice the color of somebody’s eyes, that Doreen’s breasts had popped out of her dress and were swinging out slightly like full brown melons as she circled belly-down on Lenny’s shoulder, thrashing her legs in the air and screeching, and then they both started to laugh and slow up, and Lenny was trying to bite Doreen’s hip through her skirt when I let myself out the door before anything more could happen and managed to get downstairs by leaning with both hands on the banister and half sliding the whole way.”
I can see the scene here and the immediately following one as VV's interpretation, but since Doreen keeps seeing Lenny through the rest of that month, I read it more charitable on Lenny's part. Esther describes them as getting more and more crazy about each other, while she's the obvious third wheel. I can see parallels to modern interpretations of the "Baby, It's Cold Outside" song lyrics, navigating sexual encounters with social mores of the time.