N Polyamory, also called a "Fluid Chain", is a type of quad polyamorous relationship structure. It is a relationship involving four people, generally two preestablished couples, where one member of one couple is also involved with one member of the other couple. For example: A and B are dating. C and D are dating. B and C are also dating. However, C is not dating A, and B is not dating D. A and D are also not dating.