can't orgasm

i've been masturbating since i was like 12 and i'm always able to get off so easily and when m boyfriend fingers me it feels SO GOOD like better than it's ever felt by myself and the buildup is so good but i can't relax enough to release and cum. does anyone else suffer with this problem? what can i do to fix it? he thinks i'm lying when i tell him it feels good cuz i never cum