Why do nerds have trouble with women?

Hi, I am a bit of a Geek/ Nerd... I like star wars, play warhammer, like comics, like science and maths, watch documentaries on TV, believe in aliens and UFOs and the list goes on.... I am still a very nice guy though, and I do go out with mates. I am not particularlyy ugly, I dress a bit nerdy (like wearing a Darthvader jumper, but that's part of my personality. But I constantly have trouble with women...so my question is why do women find nerds/geeks undesirable?