Losing my best friend?

She is in the honeymoon stage with the guy right now..its the stage in a relationship where everything seems like a bliss..I don't think she is replacing you I think she is just blinded by love sorta thing. They will get ped the honeymoon stage and start seeing each others flaws. They will either still love each other or hate each others flaws. You just have to be there for her and be happy for her no matter how much it seems like you are getting ditched. Why don't all 3 of you guys hang out? Get to know him a little better become friends with him.