Okay, let me explain this from my male point of view.
The reasons why this cvm dumpster deception exists stems from the reason why men don't want to commit to loose women, if they can choose. That reason can be explained through primal biology, but to keep this from being even longer, it's a gut feeling. It's an instinct. There is nothing that "teaches" men to feel that way and no "teaching" will make it go away, although there are ways to deal with it. That clear? all right. The problem for men is that we cannot know a woman's past behaviour and we cannot know whether she is lying about her past behaviour, while at the same time we need to know, so that we are not "tricked" by a woman. Women know that we are trying to avoid making a bad deal/being cheated/tricked, so they perfect the art of lying to men and many women will rationalize their own lies to avoid cognitive dissonance (ie. a bad conscience). They do this in a variety of ways. They can say that men "should" feel the way she (the feminine imperative) wants him to, they can say it's "better for him", whatever will justify her deception. Men today are I think slowly, increasingly aware that what women present themselves as to you will depend on what she wants from you, and what she can get from you.
This is not a problem if you can rely on her being "innocent", by which is meant that she has not already given herself willingly to another man. Most men however are fine with her doing so because we 1) understand that women want to have sex too and that it's fun, we actually don't want to oppress women unlike what feminism says, and 2) if she still has her highest emotion (read Desdinova's high score theory) available to us, then the best of her is still effectively unspoilt. The problem today however is that women have been let loose completely, and give themselves out like wh0res. Maybe not to you, but we know that at least some guys had enough looks, money, status, and/or good game for her to be no better than a wh0re with him. She makes it easy and compromises her integrity, her character, for the guys she really wants. We don't want to be the one pretending to have something "special" with a woman like that. We feel like suckers. But we know that women do what they can to try to present themselves and lie to us as if they "are not like that", even though we know that they are. It can also actually be in her interest to reinforce that other women ARE like that because it makes her seem more unique and desirable if we buy her lie. This makes us not only reluctant to commit to and invest emotionally in them, but also reluctant to trust them at all.
When you combine this with the steady diet of lies men have grown up on, men can turn resentful. We are made to believe a lot of things about women and gender relations that are lies. Men invest themselves in the blue pill, and then find out that the ideals and beliefs they stood up for were deliberate falsehoods. Most men would not have a problem taking a genuine, honest, loyal woman who has had sexual experience with men she held up to the same standard as you, and this is what blue pill men believe women are and do, but we know they are not and don't.
In the end, it shifts men's approach. Now we arrive at the answer you are seeking. Instead of presuming innocence until proven guilt, we presume guilt until proven innocence. The catch of course being that we both have no way to prove their "innocence" and that we know they both want us to believe they are "innocent" and do what they can to trick us into thinking they are (I put citation marks because I mean in terms of the metaphor, not in terms of virginity which as I said before most men don't require, and indeed in the red pill we have debunked the idea that just because a woman is a virgin she is not or could not turn into the way other women are. We wouldn't trade honesty, loyalty and integrity for virginity and we can live with not having the latter, especially if we like the other woman more). If she has fvcked on the first date before, why should I respect that she's "not that kind of girl"? If she had a drunk ONS before, why should I take her seriously now? If she felt so strongly for someone before that she wanted to fvck him immediately despite claiming shes "not that kind of girl", how comes she doesn't feel that with me? If she's "not looking for a hook up", why does she have pictures that are basically strip teases? If she used to be a party girl but wants something serious now, why should I be the guy who can't fvck her like she let the other guys do "for fun", but have to pretend that this is "genuine" and "special"? and so on.
We have a (unfortunately very well-justified today, which is why we think about it so much) paranoia that we are making ourself into the fool. Like I said before though men can deal with this, and there are basically three ways they do: They are blue pill and deny their own gut feeling, or that "their girl is like that". They are red pill and try to find a needle in a haystack, and risk that it is actually not a needle but a well-camouflaged hay. Or they are red pill and to various degrees don't invest emotionally in women. Women themselves create and support this environment (contrary to what women believe or perhaps rather want to pass it off as, that it's mens' fault - which it of course is, if you have the perspective that feminism was a sh!t test that men have utterly failed). Another thing is the "notch count", which is a status competition among men (we know that fvcking a lot of women = women apparently desire you because you get them) and women (women respect and desire men who other women want and men who have status, this is what causes it to be the mentioned status competition among males) and a way to mitigate ending up with a promiscuous woman as we can then have greater "accomplishment", thus feeling like less of a sucker. Most men actually don't want it to be this way but we are forced to accept it because women have made it so.
What can you do? Understand his perspective. Then actively bring up and communicate with him about his perspective, let him talk. Then be honest to him about whatever he wants to know. That's option one. Option two is you can do like most women and lie in whatever way feels most comfortable to you that so you maximize the odds of getting your needs met.
Hope I helped.