This sounds like an amazingly bad idea. Even though divorce is common, at least there is the intention of staying together for a long time.
Paying off a house is going to take 10 years minimum. Imagining that you will all still want to live together in ten years time would be pretty naive.
What is the mechanism when one or more people want to leave? What about where someone fails to pull their weight in terms of property maintenance, or causes property damage?