I'm a women and I've never had any close girlfriends. All my good friends are male. And you are right it's difficult for men to maintain a platonic relationship with a women. For the most part the women has to set the tone. I also was in a relationship with a guy an hour away and he was a bit disturbed by relationship with one of my very good male friends but he soon realized he had nothing to worry about. It's up to your girlfriend to put you at ease, perhaps introducing you guys may help.

As for visiting guys online so soon that I would worry about. Is there some way you could make her aware of the dangers in this? I say support her penchant for having male friends but definately speak up about her visiting practical strangers.