Keeping it short, me and him are best mates and he evolved to become a ladies man, on the good looking tall side, its as if, he keeps getting laid every other month, especially with older women.More recently, hes become flirty with my younger sis.Shes finishing her High school and to be honest has become a pretty girl herself, so yes i can understand shed gather attention, but i was never worried as such, as shes a good girl.Now given me and him have proximity and he frequents our common circle, they both interact alot.All this while, shes been seeing him as her bros best friend(like a brother only) and hes been seeing her as his own sis.But right now, since hes laid quiet a few women and since shes become pretty, i,m having this "complex" of not allowing them to speak since i feel the tone of conversation is bordering on flirting and shes opening up. I dont know why i feel this way, maybe i am insecure?.Maybe not!.