the answer to a problem where some people not understanding that configuring does not give the legal protections/obligations of marriage is not to sneak those obligations on cohabiting people.
Legal contracts should be intentionally entered in to. The idea that you can accrue a common law spouse is unfair and takes the choice away.
It’s also really unfair to many women. Women are not all hapless dependents on men, or victims, or any of the other things these kind of weirdly paternalistic policy ideas seem to be premised on.
Nor is it the case that cohabiting without marriage inherently makes women vulnerable. For women who maintain their careers (especially if they’re the higher earner), not being married may be advantageous. Similarly for women who came to the relationship with their own assets. Being married may be a truly terrible idea for them.
Having children with someone does not need to mean that you have to be entirely financially interdependent. Issues can (and do) arise when one partner - disproportionately the woman - reduces their financial independence by going part time, becoming a SAHM, taking a lower paid job, and so on. Marriage is a contract that may be important for women choosing to do this.
But it is not necessarily wrong for a couple to decide they want to maintain financial independence even if they are living together and raising children together - so long as no one is tricking anyone else.
The problem where some women think having children creates a kind of common law marriage so they make themselves financially dependent on a man who has no legal obligations towards them may well be exacerbated by policies like this. Or the problem where they believe a ‘jam tomorrow’ engagement ring does the same. Sure, it might mean they accrue some claim on the equity in the house, but that’s still not equivalent to a marriage contract (which encompasses so much more).
Women in these situations may believe they are adequately ‘protected’, when they very much are not. Problematic men are likely to choose to ensure their assets - pensions, personal savings, investments - are beyond the reach of this law, while ensuring that the equity in the house remains minimal to reduce their financial risk in cohabiting.
This is the sort of policy intervention that may be relatively easy to achieve in practice, but it fundamentally misunderstands the problem so it cannot possibly solve it. Instead it creates a new set of problems to go along with it.
The deep set cultural problems of patriarchy mean than women are generally disproportionately disadvantaged in both directions.