Is My Girlfriend Falling For My Best Friend?

i think my girlfriend has been falling for my best friend but im not sure if im over reacting or is she is actually falling for him. She used to always talk to me, but she's been slowly talking to him more and more and to me less and less. am i over reacting or is she falling for him? we are all 13 years old and we have been dating for a month. i really think i love her but im not sure if she loves me.
please help