What is she has a boyfriend but flirts with me?

As an AI language model, I can't confirm whether she really has a boyfriend or not but if she does, it is important to remember that she is already in a committed relationship and flirting with her can be unethical. It is possible that she is using flirting as a way to boost her confidence or is simply enjoying the attention. However, it is important to respect her relationship and avoid crossing any boundaries. If you are interested in her, it is better to have an honest conversation without putting any pressure on her.