I've had four partners who had never ejaculated before but who did when we were together. All felt that it was initially a combination of continuous clitoral stimulation and mulpiple orgasms. One summed it up as being so much into the experience that her body just opened up totally. I don't know if that's just how she perceived it or whether other women see it that way too.

Try getting your partner to rub the rough spot in the vagina just behind the clitoris while he or she tongues you or you masturbate. Keep going through the orgasm if you can stand it. Forget about your partner and everything else except the next explosion - then, when it happens, keep going again. I'm sure you will get there just as long as you don't will yourself to ejaculate or notice if you don't. Relax and it will happen.

Three of the four partners I mentioned had their most prolific releases during their periods. If you're both OK with that, it's maybe a good time to start?

I can think of nothing that pleasures me more sexually than to be with a woman while she is ejaculating. I wish you and your partner well in your quest.