If you mean Laura, she cares *a lot* about her public image. That's why she hides the kind of sex she likes from Harry, even vanilla stuff (It's implied that she did doggy with previous partners, not Harry).
And you may say: "But that reasoning is bullshit, it's obviously Option 1 if you believe the people around you love you genuinely." And you're right, it is.
My personal theory is that Laura is shown early to have trust issues (jealousy, etc.) and goes silent treatment whenever she's angry, so that already builds a background for her to not communicate bigger problems (like *the plot problem*) openly to Harry. Later on,
it's probably copium for liking the dick and being degraded despite herself. Submission comes with the temptation of letting go of your rational, overthinking self. That temptation, not just the dick, was what hit Laura like a metric ton of heroin.
And also porn logic. Don't dismiss porn logic.