"Do you have a boyfriend?"
"Sadly, no." (a wee bit of sarcasm there from yours truly.)
"Hey, but you're pretty cute. Why don't you have a boyfriend? Why not?"
"Uh. I don't know. I'm nice to old people, small children and I don't kick puppies, so I'm not sure."
Gentleman, it's really hard to answer that question. Please don't ask it. The only thing that's worse is asking why I'm not married.