Yet if you take that view then by sharing in the mortgage payments partner A may have become landlord to partner B and renter’s protection might apply to partner B.

> The general rule is that property owned prior to a marriage remains the separate property of that owner.

Well, that's one possible rule; it's not the only/universal one.

(As a traditional ceremony might say, "with all my worldly goods I thee endow". That doesn't sound much like maintaining separate property...)

Traditional ceremonies aren't contracts.

Not sure why you've been downvoted. This is how it works in my country and I think this makes sense.

Because the topic is not "what's the default legal situation".

But if you don't discuss beforehand and come to an agreement, the default legal situation applies.

If three was a mortgage on the property the payments on the principal are presumably community property, and the appreciation of that post of the value.