Don't know of a specific contract you should use, but make sure you create a 2-of-3 multisig transaction, and hire a reputable arbiter to control the 3rd key. Seed the private keys with the text of whatever you choose as your marriage contract, including any assets you wish to provably and explicitly share. Any liquid assets could be bitcoin in the actual address.
This! I like it. Rights to our assets (in this case, "our" bitcoins) is the incentive to abide by the contract. The 2 of 3 give us enforcement. This doesn't need to be on the block chain (I don't think...), but each of our hashed signatures on the contract should be. I do trust her. I trust that she is working in the same direction I am in life, and will generally be a reliable partner and asset. This is a mutually beneficial agreement.
The purpose of the contract is to establish the terms of the agreement. Otherwise, what is hell is a marriage? Why get married? If people had to actually define the roles in a marriage agreement before getting married, you have a lot less ill-conceived marriages, and a lot more lasting agreements.
There are obviously other agreements that need to be spelled out for the state to recognise in situations where it is inevitable. Those are not what this thread is about, but I'll happily take whatever input down for when we sit down together to sort out the rest of the paperwork.
