I am guessing this is a case of unrequited love? Am sorry you're hurting.

Who knows why the lady in question doesn't see you in that way (I don't think generalising helps, I could say the same about a few men I known!).

Have you ever said anything? Sometimes speaking up may set the ball rolling. If its not mean to be though, its not meant to be. Romantic love isn't usually a conscious decision. Even if a person knows you love them and yet doesn't feel the same, sometimes the feelings are just not there - we can't make ourselves like another. Try not to take it personally.