So, while guys think highly of GoodGirls and often wish they could fall for a GoodGirl, they are more likely to become good friends with a GoodGirl than to be interested in her.
This is similar to the phenomenon of the NiceGuy?, who's such a nice guy that anyone he's interested in either won't notice his interest or couldn't possibly return it for fear of ruining their friendship... only to end up frustrating him endlessly with tales of their love life (without him) and perhaps even the line "I'm going out with this guy who kind of reminds me of you..." Usually the Nice Boy eventually turns into a celibate evil maniac and takes over the world.