Friends.......................…

so, i have this friends that's been my best friends for years but suddenly within the last week she seems to have decided she hates me... it could have something to do with her girl friend who used to have a thing for me..... or i could be being narcissistic :L anyways i was just wondering what you would do. she's started bitching about me behind my back and has told people she's just 'sick of being friends with her' her being me. should i just leave everything and see what happens or....?