My boyfriend cant ejeculate

That is a common problem with men of his age. He should see a sexual therapist or his doctor. There are medications that he can take.

or

Maybe you guys are just doing the same thing over and over. Try watching an erotic movie with him before, and try some foreplay. Mix things up a little bit, ya know? Don't always make love in the same position.

Good luck

Contact a doctor and get a physical, that is all I can think.