I'll stick with my original reply - it's down to the stress. A man finds it difficult (impossible?) to get an erection when stressed. Relaxed - no problem unless there's some other underlying problem.
As far as my understanding goes, a woman needs to be in a similar (relaxed) frame of mind in order to get any
kind of fulfillment from sex, let alone be able to orgasm.
I know, sticking my neck out a bit, but I hope it helps (try Googling stress, female orgasm). Best wishes