What does it mean if a 12 year old boy acts like he likes you but tells someone he likes them and it gets back to you?

it means that theres a possibility that hes lying to one of you and wont tell you. if he keeps this on confront him and tell him that he needs to choose one person or the other. and if it isnt you then dont be upset about ir because the 12 year old wasnt even worth easting your time with.