I think it's a mistake to tell yourself you could never love a woman, but regardless, when the question comes up an indirect and playful answer is best. Emotional talk can be a huge turn off to women unless they REALLY want it, so better to be safe and make them pry it out of you so you know for sure they really do want it. Saying something absurd, then doing the opposite is a good "technique". "I don't know. I love your ass, does that count?" or "No, I totally hate you." then kiss her.
I agree though that you shouldn't ever give a straight answer and say yes even if you are in love with her. If you love her it should be apparent in your actions. You plan fun dates, you make her feel safe, you have great sex, and if you're in love and exclusive you're not dating other women. When a woman asks you if you love her that's really all she wants to know. She wants to know you're not going to leave her because she doesn't want to lose you, and if you do the aforementioned things then she will know that you are, even if her emotions sometimes get best of her and she worries you might not.