I understand your defensiveness over feeling that what I'm sure is a loving and nurturing union between you and your partner is being compared to forms of slavery, and you raise good points why a direct comparison would be overblown. However, I would be more careful with your choice of words here:

> The entire institution of marriage is meant to prevent one spouse from controlling the other by simply making ownership joint.

The way this particular point is phrased makes it sound like this was always the case. However, it is a very recent change in how the laws work, as a direct result of mainly women fighting for their rights. It used to be the case in many countries that only the men can decide to end a marriage, and I'm sure that is still the case in many places.

Maybe the legal framework of modern marriage in California is decent at guaranteeing equality, but that is not something to be assumed to be the general way marriage works, let alone something to be taken for granted. And I'm sure you'll agree that the institution of marriage is important enough that it deserves critical examination.