Mate I've asked the same type of question here and got the same type of responses from the same people. I for one know exactly where you are coming from. I have no problem whatsoever splitting assets that are accumulated after commencing a relationship, but it's utter ******** that you can spend years and years doing the hard yards workwise, overtime, second jobs, savings your *** off etc and then have someone come along and claim half of it. That so many people on here seem to baulk at what is a fairly important concept (asset protection) is quite amazing to me.
Having said that I don't believe these dafacto laws were brought in to allow people in situations such as yours claim half your stuff. natmarie has it pretty well covered in her post.
Having been in relationships I thought would last forever I say you can't be too careful!
Maybe when a person is in a long term relationship where both partners share the same goals, and both work hard towards those goals then the perspective is quite different. Its not that we are all naive and think that all marriages will succeed. If GoMichael left the money would be the least of my losses. I also strongly believe that if my focus is to protect myself against him (whatever that would mean) then I would achieve far far less.
I can't imagine being in a realtionship where one person is not pulling thier weight or not sharing my dreams so I can't comment from that perspective.
Life really is short and the only way we can protect ourselves is avoid relationships, don't invest, never start a business, never cross the road. I am not prepared to bunker down - life's too short!