On one hand she is an interesting attractive person, on the other I'm well aware of the pain of being interested in people unable to return ones interest.
It recently occured to me there was one other thing that led me to be interested in her over an actual lesbian. I'm not so hot at that initial awkward phase of getting to know someone. It was really convienent to be able to go chat with her during dead times while at work. That low barrier helped me spend enough time to feel more comfortable around her.
I've been rather bad at putting in the time to get to know actual lesbians. Part of it has been lazyness, part of it has been my inner guilt at using a car to go places, part of it has been my fear that most people aren't interested in the things that I am.