I have been told to "stop" while having sex with a girl before. (Ego buster for sure!!!)
It seems she had a boyfriend and got second thoughts after she got hers. (True)
I stopped what I was doing in mid plunge and got the hell up. (Didn't get mine)
I couldn't even think to continue the sex and all I could do was tell her it was OK. (She felt bad about leaving me high and not-dry)
That said the law should include precise language to be used by the girl if she changes her mind in mid stroke.
I mean if a girl says "get off you fucking piece of shit" it could be taken the wrong way, with a Dominatrix for instance!!!