What? You didn't get the Poly Manual when they sent you the decoder ring for joining the club?
Do a search on "nonviolent communication". This should give you some useful tools for negotiation in relationships.
As for negotiating after the fact. It happens. Nobody can plan for every contingency.
Me: 48 - Married, straight, male
Shiela: My wife.
Suzanne: My FWB
Adam: Shiela's LDR