Okay as an example I have two neighbors - one is male the other is female. I often have hallway (I live in a condo) discussions with both of them. The male friend I feel comfortable asking out for coffee or going for ice cream. I'm not real comfortable asking the female friend out anywhere because I feel one of us might think something is going on. There's also a good chance of the physical thing, i.e. I'll be so busy looking at her hair and eyes that I'll forget what we were talking about - this isn't a problem with the guy. Maybe it's just me I'm always in need of more affection.