At least where I live, there is no distinction. As soon as you've lived with someone for 6 months, you're considered common law. If you separate they're legally entitled to half the stuff you've accumulated while together.
While together is much more reasonable than absolutely all of your assets as with marriage though.
That's not how it works with marriage here either. It's only assets acquired during the marriage that is split. There are some exceptions, I'm not a lawyer.
but if more men don't want to get married, women may not be able to find a suitable partner. Also, there is a gender disparity in location (more men in small towns and SV, more women in NY, LA)