"He had brought home a lady he had known for quite some time for a couple of drinks. They had never got past the drinks. As soon as they sat down next to each other on the sofa, he realized nothing was going to happen."
The implication is that he brought the lady home for a couple of drinks in the hope that they would then move on to some romance. Your quote suggests that although he had known her for quite some time, they had never got past the drinks in such circumstances – that is, there had been no romance after the drinks. But as soon as he sat down next to her on the sofa he realised, for some reason, that there would be no romance that night either.
not a teacher