When you get that "rush" every time you see her; when you'll go out of your way just to talk to her, even if it's a simple "Hey, what's up?"; when you find yourself thinking about her for hours on...
You don't. They would know it if they were. The smartest thing you can do is let them know how you feel about them, & see what they say. It could be they are shy or scared of sharing...
You can't make someone love you, but if she is interested in you then just ask her out and let her get to know who you are. NEVER change who you are for the sake of anyone else if you are a good...