But really the female association is due to the fact that a guitar has curves, is GREAT to look at and is beautiful, and let's face it - most guys don't like the thought of something that is a "guy" being right up against them or in their lap all the time. Not saying there is anything wrong with it but I much prefer females.
Now, I have heard of female guitarists naming their guitars after guys and there are some guys who name their guitars with male names but generally speaking most guys who name their guitars use a female name. Just look around on guitar forums. You'll find out!
Another reason is that for a lot of guys, their #1 guitar is like their wife or soulmate and is always there for them and so that's another reason. I know my Ruby is definitely my "musical" soulmate and always will be. I never get tired of playing or looking at "her" and always feel right back at home when I pick her up. Sorry for getting sappy, but a lot of guys have a deep emotional bond with their #1 guitar. Ruby will be buried with me. I've already given instructions. BB King and Lucille is a perfect example of that. Ruby is the one I would grab in the event of a fire. Ruby is the one that always puts a smile on my face out of all of my guitars. I would live in a shoebox before I'd even consider selling her. I would live in an empty house. She's the one that's always there for me no matter what. She will have to be pried from my cold dead fingers. We are "one". Soulmates for life!