"Good, if this gets too intense for you, you can just say 'Stop! I want to fuck you and marry you and give up this stupid quest!' OK?"
You say that seems like a long safe word...
"Yes, but I want to plant that thought in your head, so just keep thinking about it! Only when you say those exact words will I stop, got it?"
Yes, you nod. You have given her absolute control during these sessions, so you naturally go along with it... but the words do seem funny...