It also proposed that people who have children, have been together for 10 years or more, or who have built or sacrificed careers because of the relationship - should be eligible for Family Income Sharing Arrangements (Fisa).
Under a Fisa, the partners would be required to share their combined income for a limited period after they separate, to ensure the economic advantages and disadvantages from the relationship are shared more fairly.
Another reform to the law suggested giving courts greater powers to share trust property when a trust holds property that was produced, preserved or enhanced by the relationship.
The Law Commission is now seeking feedback on the proposals before making its final recommendations to the Government in 2019.
Last year, the Commission published an Issues Paper, and asked the public to comment on whether they thought the law was working well in contemporary New Zealand.
Many of those who commented thought some aspects of the law needed to change.
An article by the Herald last week also looked at the University of Otago research that found New Zealanders want the equal division of property after a breakup to be reconsidered.
While most people generally support the existing law which requires a 50-50 split of assets, a strong majority also believe it would be fairer to depart from the rule in certain situations.
In a scientific survey of 1400 people, 72 per cent agreed that a person who paid an entire house deposit should get it back after a break-up rather than split it.
And 60 per cent said a person who gave up their job to raise children should get a better deal.
University of Otago Associate Professor Nicola Taylor, from the Sociology, Gender, and Social Work department, said there had been dramatic social and demographic changes in New Zealand since the original law was passed - in particular people marrying or having relationships later in life.
That meant the existing law no longer matched up with New Zealanders' ideas of fairness, she said.
Commissioner Helen McQueen said dividing property when relationships end is often a challenging task, and one which typically comes at a time of emotional upheaval.
"Partners should be helped at this time by a law that is clear and that accords with what most New Zealanders would think is fair," she said.
"We have developed a package of reforms that we think reflects those expectations and updates the law for contemporary New Zealand."
The Paper can be downloaded at Review of the Property (Relationships) Act 1976 and feedback can be given until 14 December 2018.
The Law Commission will publish its Final Report in 2019.
