THE first time you see Lena Dunham’s character having sex in the new HBO series “Girls,” her back is to her boyfriend, who seems to regard her as an inconveniently loquacious halfway point between partner and prop, and her concern is whether she’s correctly following instructions.

“So I can just stay like this for a little while?” she asks. “Do you need me to move more?”

He needs her to intrude less. “Let’s play the quiet game,” he answers.

The second time, she’s an 11-year-old junkie with a Cabbage Patch lunchbox, or so he tells her, commencing a role play in which he alone assigns the roles. He has highly specific fantasies, and she’s largely a fleshy canvas for them.

You watch these scenes and other examples of the zeitgeist-y, early-20s heroines of “Girls” engaging in, recoiling from, mulling and mourning sex, and you think: Gloria Steinem went to the barricades for this? Salaries may be better than in decades past and the cabinet and Congress less choked with testosterone. But in the bedroom? What’s happening there remains something of a muddle, if not something of a mess.