My guy best friend’s girlfriend doesn’t like me?

[Loveydove]

Me and my best friend John have no romantic history nor do I want to be with him. I see him as a younger brother. Before they started dating me and her were kinda cool not friends but on good terms. Now she always has an attitude with me, talks about me behind my back, laughs at me, etc. I asked her twice on multiple occasions if she had an issue with me and she claimed she did not. But she acts like she does.
I’ve been nice... bought her a birthday gift... even given my friend advice on nice things to do for her because i genuinely want him to be happy.

I told him that I’d take space so it doesn’t seem like he’s picking my side and not hers (even though technically there’s no sides) i try my best to be a good friend and support but she’s mad because of me and I don’t know why and he’s mad because of the space.
what do i do?

[chriscdi]

try to find a perfect opportunity to tell her that you only see her guy as a brother and that there's nothing between y'all and there won't be, if she changes then that was the problem