Uncomfortable when someone is staring at you?

which reaction means some one is uncomfortable with you staring at them mostly for a woman if they feel it's too rude have an attitude about it they just talk more about any thing just to divert the attention of the person staring at them. or staring back and smiling or just staring back i am asking this because this guy was staring at this girl i like and she said it made her feel uncomfortable so she started talking more and even said she had no interest in him but with me when i look at her she looks back and smiles. why do i take more conversation as her liking some one