NOMTY.
"Your" problem(?) raises a few questions:- How old is your man? How long have you been having sex? How often does he mastubate? Does he mastubate prior to sex? Does he take any medication that can cause this problem? Does he ejaculate with oral sex?
A bit of advice may be simpler with more facts!

me and my boyfriend have always had great sex and made great love but recently he can not ejaculate he has type 1 diabetes and suffers with high blood preasure i also do feel he drinks more than what he should he is nearly 34 and im 23 so it is frustraiting i feel its me but i know the more i talk about it the more it knocks his confidence i think ha has resigned to not bothering anymore so now we hardly make love at all what can we do please. llouise

He is 28 years and we been having sex for about 2 years . I am not sure how often he mastubate. He doesn't mastubate prior to sex and there are no medication. He has no problem with eraction, can go for hours. he feels something building up but can't cum and/or ejaculate. He has never come with a women, only by mastubating.

It's a mental issue then, and one that you and he need to work on together. He can try masturbating almost to orgasm and then having sex, and slowly work it so he has to masturbate less and less beforehand, until finally he doesn't need to masturbate at all and can orgasm just from sex.