<human>: So I (17/f) and guy (m/18) have been dating for 6 months. We have known each other for over 2 years and have always liked each other but haven't actually started dating till now. We are both really happy together as of now and there aren't really any problems between us.

I think my friend (f/16) has a crush on him. She is always really bubbly and it seems kind of flirtatious to me. It may just be me being paranoid but that's what I think. She is always usually pretty bubbly but she was acting different when it was just me and he wasn't there. She wasn't bubbly and friendly to me at all when he wasn't there. It was very strange for her. She sits with him at lunch along with some other friends we all share but it just makes me uncomfortable. 

I don't know if I should say something to guy about it, or my friend, or if I should just say nothing at all. I don't want to give either of them any ideas. I know guy wouldn't really do anything with her but I just feel uncomfortable that she is being so flirty. What do i do reddit??

Condense the text into a few key points
<bot>: my friend is flirting with my boyfriend and I don't know if I should say something or just ignore it all.