Can't orgasm during sex

I can't orgasm when I have sex. I know I need clitoral stimulation, because I use a vibrator on my clit and orgasm just fine when I'm alone. But I can't get there when I have sex with my fiance. Idk why. When we first started having sex I was able to rub my clit with my fingers while we had sex and that worked, but it just doesn't do it anymore. We've tried using the vibrator during sex too and it doesn't seem to work either. We've tried different positions and he's definitely put in the work trying to help me, sometimes he'll keep going even after he starts to cramp up because he wants to make me orgasm. I don't know why nothing works for me and its so frustrating because other women seem to have no issue. I've seen some women here on eve post about cumming two and three times during sex, how their men make them feel so good, etc etc. I know its not their fault but I get so mad every single time I read that stuff! I enjoy sex with my man and I get soooo close, I just can't get to that peak. Does anyone have any ideas that could possibly help me??? Maybe someone else had this issue and found a solution??? I'm so tired of feeling unsatisfied 😔 Its starting to effect my fiance too. He doesn't enjoy sex as much because he knows I'm not getting what I need. Please, HELP ME