Is there a good reason* why death and injury due to choking/strangulation shouldn't be strict liability offences?
I can't think of how you would find yourself with your hands round someone's throat by mistake.
Because no, there's no way of guaranteeing someone's safety if you choke them, and if they "ask for it" you'll want to be thinking very carefully about whether that's worth the guilt if they have a stroke or die.
*But she said she liked it isn't a good reason and people that stupid shouldn't escape prosecution if they're reported for a crime.