All that needs to be done is arbitrary lines drawn. Courts can do that just fine as cases arise.
Starting from scratcvh with no legal basis? Thyat process would take decades, in every state.
Get rid of the whole alimony system (in all kinds of marriage) and you eliminate more of the trickier problems.
So, yougive up your career for the sake of teh family, and when your spouse leaves, you automatically get nothing? I don't think I could support that.