Complex sentence: Maureen wants Joanne to understand that she's only having fun, while Joanne wants Maureen to follow the rules of relationships that Joanne lives by and stop mocking her for her Type-A personality.
Split into simpler sentences: Maureen wants Joanne to understand that she's only having fun. However Joanne wants Maureen to follow the rules of relationships that Joanne lives by and stop mocking her for her Type-A personality.