I think part of this is because many women tie their attractiveness to a man just magically ejaculating. Men are supposed to have the problem of holding back, not getting there (again, this is all society BS) so when a man prefers to masturbate, it’s implied that somehow it’s the woman’s fault that he has to “resort” to that. I think that’s where this comes from, and it has dysfunctional roots. Of course self-pleasure feels different than someone else doing it, and shouldn’t be embarrassing, and women shouldn’t feel like their attractiveness hinges on men mysteriously ejaculating.