How do you know a girl is lying to you about how she feels?

a girl is lying to you about how she feels if she is not looking in to your eyes when you are asking or talking about what she really fell for you. another thing is, if the girl is not going out with you everytime you ask her because it only means that she is not trusting you. that is the common signs to know a girl lying about her feelings. the only person who can answer that is you, why don't you observe her and ask her friends? i think that's the best way to know the answer.