I don't think I have it wrong at all. Ayn Rand should have had Dagny (or whatever her name was) charging for her services rather than giving herself away free without a commitment from the man. The book gets weak here, because it doesn't show the negative consequences of their actions. With her self-esteem and self assertiveness, she should have gotten $1,000 a fling.
You are right that her idealized plots necessarily left out the mundane negative consequences of sexual intercourse, but it wasn't Rand who invented that literary device.
My problem with her idealizations of sexual relations is that they appear to be from a female point of view. She seems to put more emphasis on the intellectual motives for sex with little realization of the mundane, preprogrammed, biological ones.