What does it mean if a girl is more quiet around you than before?

There can be many reasons a girl is more quiet around you then before. One she might like you but doesn't know how to approach how she feels. two she might be uncomfortable around you because of something you did, said or what she heard about you. Three she might be having her own problems and has to much on her mind that she is just with drawn. Why don't you ask her whats going on, she just might tell you.3. maybe if you said you liked her and she doesnt like you back then she will ignore you and try to do the best for her self for she can't date someone that she doesnt like.