I'm not fully convinced virgin-shaming exists. Can any men here testify to this happening: that you have been going out with a woman, she's already attracted to you--it's going well, but then you mention you've never had sex at an appropriate time and she insults you or suddenly switches up on you

Personally i'm not against dating a virgin per se. But my immediate assumption is that he'll look down on me for my experience. And usually i'd assume the cause for this is something that makes us incompatible (religious, or is just straight up unattractive). But none of this is to say that being a virgin is inherently bad, just the possibilities surrounding it. Theoretically, if I met a guy who I was into, and it was somehow clear to me that he wouldn't see me as a whore, then it wouldn't make a difference.