Gosh I was trying to stay out of this conversation but .....

I agree....the necessary motion usually is interrupted when the man O's to continue to get the woman there at the same time....

That is a two way street.
I have never O'd at the same time of my partner if my memory serves me right. Sometime it is because of there sift in movements but other times it is because quite frankly to be blunt (theres a surprise). When I O I force the persons member out of me with the contractions I have which kills it for them.

Making a joint O impossible or improbable.