He cant ejaculate

Me and my boyfriend been going out for a year now. The sex is great but everytime we do have sex he doesnt ejaculate we could go on for hours and nothing would happen so, when we done having sex i help him jerk off and he cums that way but he jerks off in a weird way and when he tries to do it the "normal" way nothing happens. He wants to be able to cum during intercourse but he just can't, smh i dont know what to do . . .