You shouldn't dis-invite people to events.
Thelma has planned a dinner for her friends, including her unpolished cousin, but just found out that a very refined man whom Thelma likes will also be attending.
Thelma wants to impress her crush.
Thelma decides that everything will be alright anyway and looks forward to seeing her cousin at the party.
Thelma calls her cousin and tells her the party is cancelled to avoid having her cousin embarrass her.
Thelma's cousin has a great time, and so does Thelma's crush who is impressed by how gracious a hostess she is.
Thelma's cousin finds out the party is still on and is quite sad at having been rejected.