Please forgive me, I'm trying to keep things a bit vague but I hope it's not too annoying.
Friends A, B and C were going to an event together. Friend A said she would book and pay for a triple hotel room. Friends B and C would pay her back at the event. Friend B pulled out of event at last minute and Friend C then gave Friend A her third of the room cost whilst saying how cheeky Friend B was for not paying her third and now Friend A is saddled with paying two thirds. Friend A felt that if two people share a hotel room then they split the cost equally and that C should have paid half of the cost. Friend B is in the middle of something quite serious so A feels she can't really ask her to cover the cost.
I hope that wasn't too much of a pain to read. What does everyone else think?