We are talking about Athena, Artemis, and Hestia here, folks: the Three Virgin Goddesses. At the risk of presenting a depressingly simplistic argument, I’m gonna do my best to give you a starting point for thinking about these things. Remember, now, that ancient Greece was a pretty patriarchal collection of cultures.
So the thing these ladies had in common was that they weren’t interested in having sex with men - but beyond that they were quite different. Athena was kinda butchy with her interest in war and adventure. The perfect daughter (at least for a patriarch) she owed all of her allegiance to Daddy and that would never change because no husband - or even a mama, in her case - would compete for her attention. As a virgin, she represented an ideal of daughter-hood.
Artemis, on the other hand, was super hot. Tomboy? Sure, but in a sexy sort of way. She ran around in her short little skirt hunting deer, she bathed naked in woodland streams and ponds, she was the sort of untouchable beauty you might “flay the flayed dog” to late at night. But just as virginal daughters were supposed to be attractive but off limits until the deal was sealed with a wedding, so too was Artemis off limits. This stage - tight-bodied virginal beauty - is perfectly represented by the goddess.
And finally, Hestia. Dear Hestia. She was a virgin, but only because the alternative seemed so darn complicated. She represents the perfect homemaker. The problem with women is that once they’re sexually active, you can’t tell WHO they’ve slept with. Also, who knows whether a mother’s allegiance will be to her children or her husband (dangerous for a patriarch - see Rhea). And what about her familial obligations to her father? Hestia circumvents all of these issues. She is literally the hearth, the center of the home, and her virginity is an example of the problematic role that women played in such a patriarchal culture.