Why is he diffrent now?

he called me every day wen we wernt going out But now tht we r he dosEnt even txt anymore and at skool he act very differnt with me i asked him wy and he said he had to keep his image good wich made me feel lyk krap over the fone he so sweet n nice but in person hes a whole diffrent person now tht were going out he says everythinng was gunna change it did b ut not the way i though it would be lyk he ignores me now and still talks to his ex what shuld i do?? help