One of my characters just told the main character to 'kiss me arse'.

What was SUPPOSED to happen was the main character going to her bedroom and locking her door. But INSTEAD, they had a fight in which French was spoken and the initial 'kiss me arse' was said...

WILL SOMEONE PLEASE TELL ME WHY NOTHING THAT HAPPENS IN THIS STORY IS WHAT WAS MEANT TO HAPPEN IN THE FIRST PLACE?