What I don't want is for the UK to guarantee that all EU citizens can definitely stay and then UK nationals promptly get ejected from all the other 27 countries. That is what Theresa May is saying she wants to avoid, in diplomatic language.
I don't think that scenario is likely, but the first duty of the British government is to protect British citizens.
Nobody likes it, it is worrying and unsettling for all of us.
I don't think there is any sense that it would be the last thing decided, I think the humanitarian view will prevail, but if things get nasty then anything could happen.
We are part of the negotiations whether we like it or not.