This is a... hard anthropological claim to make. I don't claim to be an expert anthropologist, but I would note that marriage means very many things to different peoples. 'Western' marriage, as it were, is already fraught. One man and a women, sharing property? Well, what about two men, two women, or other genders? Non-cishetnormative understandings complicate this picture quite quickly. And what of property? The capitalist idea of property isn't the only one, and different understandings of property will, historically speaking, lead to different understandings of marriage.

All of this is to say that marriage is a fraught societal construct, not a societal neccessity.

This thread took a bit of a wild turn, but I felt I had to respond :)