YBR-- Where do you draw the line?

Question…where do you draw the line when it comes to your SO (significant other) having friends of the opposite sex? So have you ever started dating a guy and slowly began to realize that he has a LOT of female friends. Of course many of these women were probably there before you came, but now that you are there SO you wonder why there is even a need for all these other miscellaneous women. Here is the situation. One of my girls had been dating this guy for quite some time. When they got together he made mention of the fact that he had a few female friends, but that they just hung out from time to time when they were in town. So my girl was cool with it. Well it ended up being sushi one night with some friend coming in from out of town, then later, going to happy hour with some friend you ran into from high school, then making lasagna for some “friend” that made mention of how good it was the last time he made it, and finally the him calling up one of his “friends” that he sees often in the group setting to hang out one night. Now is this guy really just keeping up with old friends or should my girl be concerned. I mean, why can’t he hang out with his guy friends, why so many females. If he wants to hang out why can’t he call and hang out with his girl? Are all these females really old friends or women that he’s meeting and trying to spend time with on the sly? I personally am not in the right state of mind to be objective about this whole thing so I pose the questions to you. Is my girl getting played or could this dude really just like spending time with this plethora of women friends? I guess I should mention that if the shoe was on the other foot dude would be none too pleased if my girl started taking up with a hoard of guy friends in the same way.