Reminds me of doing further mathematics a-levels at school (UK, so last couple of years before uni). We had a single girl in a class of about ten, who eventually decided she'd prefer to drop the class. It was a shame as she was very bright and - at least to my memory - it was one of the few courses that really stretched us. But I can't think of any way to have created a different outcome... I think she just didn't enjoy the atmosphere created by such a group of nerdy teenage guys.