What is all this agreeing shit? Sounds like you two sit down with a lawyer and hammer out some kind of fuck me custody.
If you have to have a talk about it, it is obviously too far gone to even consider ruling feelings out. It is usually a mutual unwritten/discussed decision that is naturally accepted before you even consider making it a regular thing.
Now when you get into the realm of one person thinking this and the other thinking picking out China patterns for the wedding.