A friend problem?

me and my two best friends have been an unbreakable trio forEVER. but lately they've been closer to each other than they have with me. thsey still like me, but in cl, when we have to have partner they automatically go for each other and totally leave me. i know that ONE of us has to be left out, and normally we switch off every time, but now i am ALWAYS out. they r the BEST friends I've been able to find since kindergarten, and i can't just SWITCH, because i have no other REALLY good friends to switch to. what do i do?!?!?!?