RORY: I can’t believe I was her best friend. I feel awful.
LORELAI: Look, I’ll tell you what. If you wanna make things right, just go back to school tomorrow and let her stab you.
It’s Friday Night Dinner, so why would Rory and Paris go to school the next day, Saturday?
Rory is surprised to discover that Paris considered her her best friend, which seems somewhat oblivious, considering that Paris already told Rory several times that she feels able to ask Rory for help in a way that she can’t with Louise and Madeline. Paris has made it fairly clear that she considers Rory her equal, and relies on her – Rory fulfils a role in her life that nobody else can.
I think Rory is meant to come across as sweet and humble here, but she actually seems too self-absorbed to understand how important she is to Paris.
The Annotated Gilmore Girls 