Legal Question in Wills and Trusts in California

No. There is no common law marriage in CA.

The division of assets you refer to is for people who are married to each other. If you are merely boyfriend-girlfriend, even if you have lived together for several years and have had children together, the common law 50%-50% rule does not apply. The basis of the law is that if two people are married, both of them really share in producing the family income as even though only one has a paying job the other takes care of the house, paying bills, cleaning, buying food, etc. Since you can not measure in a dollar sense what the non-paying work is worth, the law assumes both contributed equally in producing the income.

The rule also only applies to assets/money obtained during the marriage and from common funds. If during your marriage you cash in the bonds you bought before getting married, those are your private funds and are not part of the community assets. However, if you promise the other person that you will take care of them for the rest of their life, you might end up in the Lee Marvin type of case in which the court treats the relationship as being sufficiently like a marriage to find assets accumulated during the "marriage" are community property [his girlfriend lost the case because she could not prove that].

It is unclear as to whether the community property rules will apply to people who become registered partners.

It is very important that you spell out all the economic terms of any relationship you have and that you give a handwritten discussion to the other person so that they can not say they were unaware of your position. Of course, later they can say you said to ignore the agreeement.