orgasms

i cannot orgasm when im having sex. doesnt matter what were doing i literally just cannot cum. i feel like somethings wrong with me and im so embarrassed. i can make myself orgasm but i just cant during sex or anything sexual with someone besides myself. im so frustrated idk what to do. im 100% comfortable with him and i dont feel uncomfortable during sex so i literally dont know why i cant. i cant think of anything. like sex feels good and i enjoy it but i just cant orgasm for some reason?