If you are not comfortable with what's going on, you need to tell her that you don't like it when she does those things. If her feelings get hurt they do, but never let anyone continue a behavior that you are not comfortable with. It's your body your space......
Tell her that you are fine with her sexuality, but you are straight and find it a little bit awkward
I usually try to refrain from giving advice as I am not a counselor, shrink, or your parent. I really think you should talk with your parents, they will have good ideas but as you have not talked to them yet maybe you have your reasons. My advice is not from a professional and I only know what little you have stated.
1. Decide what the boundaries must be. Flirting is a great ego boost so maybe if you would not mind let her flirt. If that makes you uncomfortable, then decide not to let her. Decide what does not bother you and what does.
2. Decide what you want to say and maybe practice it. Maybe write it all down or make an outline. If you want to remain friends include that. If you are thinking trying to avoid her because of her behavior make sure she knows that also. If you expect she will argue some points include your response in what you are preparing. Consider she may be hurt and how you will respond to that.
3. Decide on a place that you feel comfortable at for the discussion and she will feel comfortable at.
4. Tell her you need to talk and it is serious. I am assuming you value your friendship with her. Tell her where to meet and when. You need to be in control of the situation at least at the start.
5. When you meet ask her to sit down and to not respond until you finish talking.
6. Tell her what you have practiced. Then let her respond. If she wants to remain your friend she should recognize and accept your boundaries.
Many many relationships are LONG term one sided romances and loves where the other side is only friendship. That is not a bad thing and as you grow up you may discover you are in love with a boy that only sees you as a friend. You can still have a life long relationship with both the boy and your friend. There must simply be boundaries that everyone knows about and everyone respects.
That is my two cents. Take it for what is worth.
Didn't find the answer you were looking for?