I wouldn't necessarily call any of that "withholding" sex.
You may, ironically, know more about an online date before you meet, but that's not necessarily an advantage: only online can you decide not to date someone for an incredibly trivial reason (he thinks flag burning is worse than book burning?! If you meet in person, that information comes out later, in the natural course of getting to know someone, and by then, what looked to be a red flag turns out not to be such a deal-breaker. Hell, I could easily argue that online dating makes people more likely to commit to a relationship early, so they can end their exhausting, time-consuming search for love.
But thanks to sheer odds and chemistry and all that, most people are not a good fit, and so you keep dating.
This has nothing to do with gender; if anything, the men in my informal sample group are far more eager to be in a relationship than the women.
The article profiles a young man named "Jacob," who Slater tells us has been called "lazy, aimless, and irresponsible with money." Jacob himself says, "I've never been able to make a girl feel like she was the most important thing in my life." Surprisingly, one woman stuck around for five years before she left.
Not surprisingly, Jacob, in his early 30s, "felt he had no idea how to make a relationship work." Jacob knew this about himself before he ever created a profile.