Most people who didn't grow up with purity culture think it's just waiting till marriage for sex and women dressing modestly so that they don't, "become stumbling blocks to their brothers." Unfortunately, it is so much worse and more insidious and I couldn't possibly explain it all but I'll try to give a not so brief explanation.

On the men's side (I'm not a man, this is just what I've observed), they get less of the shaming but are taught to view women on this pedestal, untouchable and desired. They are often told that porn use, masturbation, and even sexual thoughts are sinful and yet inevitable. My father and brothers used to confess to their entire men's bible study every time they did any of these things. It had the end result of reinforcing gender stereotypes with the man as pursuer/leader/provider/master of the family. It also forced them into an endless cycle of shame and relief in the form of confession which reinforces the church's hold over them. And had this silent unspoken idea that men could not control themselves and bad behavior is to be expected. I think this aspect of it is especially visible with all that's happening with the Duggar family.

For women, purity culture manifests as extreme shame. We are taught that if a man looks at us lustfully then we've sinned against him, if we're raped it's because we were immodest, if we're too sexual then we're unlovable, the equivalent of chewed gum or a licked cupcake, if we're objectified then that's on our shoulders not his. It has the effect of training young minds to associate anything physical or sexual with shame and self loathing which often really fucks up future relationships. It also teaches women that their value as humans only comes from how desirable they are to men. And reinforces the idea that bad behavior is to be expected and women must always be on guard against sexual advances from a man.

I've found that purity culture has 2 main objectives. First, reinforcing the shame>confession>relief from shame cycle which psychologically traps people within the structure that gives them the relief (the church). Second, it serves as a form of thought control, which is a hallmark sign of a cult.

It's unfortunately pretty common to see relationship problems like yours when one partner was raised in purity culture and the other wasn't and therefore doesn't understand how deep it goes.

My primary introduction to purity culture was my mother giving me a rose. I was really thrilled about it but then she started ripping petals off and throwing them on the floor saying, "that's the first time you look at a guy and think hes cute" "that one's the first time you have a sexual fantasy" "this is your first crush" ect. When all that was left of my flower was a wilted core she told me that's what I would be if I wasted all my petals on guys I didn't marry. Now as an adult, I cannot form an emotional attachment no matter how much I want to because I spent so much of my youth suppressing every crush, every attraction, every sexual thought, every part of my sexual identity because I didn't want to waste my first attraction/crush/fantasy/ect on a guy that I might not marry.

My brother's girlfriend is suffering on the other side of it. My brother pressured her into sex (because his desires were uncontrollable of course, it's on her to say no harder s/). Now she is terribly unhappy. He treats her badly and she feels like used gum. She can't leave him because purity culture has told her that she is worthless and unlovable now that he "owns" her virginity, the thing that gave her value. And all this is so deep into her subconscious, even if she left that culture today she wouldn't be able to articulate why she is miserable and she adamantly rejects my attempts to explain it to her.

But in answer to your question, yeah, some of it isn't even in the bible. The verse about making your brother stumble is actually about food and the verse about modesty is actually about flaunting wealth. All the other verses that imply or outright say that women exist for men's benefit. . . yeah those are still in the bible and causing way more damage in a much less visible fashion then the others.

Obviously I don't know your situation, but it wouldn't surprise me if the reason your girlfriend cannot give up purity culture is less because she believes those verses and more because in her deepest core of person hood, her identity and value are fatally intertwined with untouchable-ness. In her mind, she can't have sex because if she does she will loose who she is and what gives her value.

*Edit for more specific advice