Slavery - well, chattel slavery - is the legal ownership of another person. You can't own something that doesn't exist, so slavery logically must therefore recognize the existence of the individual. In the antebellum US, slaves couldn't legally marry because they did not control their own legal person.
Marriage is the creation of a new legal and social entity from the dissolution of the individuals entering into it.
I'm male; my wife is female. In the sense that I "own" my wife, she "owns" me. In truth, it's slightly more subtle: we have decided to minimize the distinction between ourselves as individuals. Making a traditional marriage work requires enormous trust in both directions.
"If we go back and take a look at the earliest written records that we currently have of human civilization — the ancient Mesopotamian texts — it becomes clear that marriage was very similar to slavery; marriage law looked a lot like property law. This is described in a lot of details in the Code of Hammurabi. You just have to consider the fact that the Akkadian words describing a husband (be-el as-sa-tim) mean “owner of a wife” to realize that, just like a slave, a wife was considered to be a man’s property. A woman had to address her husband with “master” or “lord” just like a slave addresses his master or a subject his king. And to this day there are still cultures where the words used to describe a husband literally mean “owner of a wife.” Consider that in the bible, when god decides to create a woman, he does so to create a “helper” for the man, later adding that “man shall rule over woman.” In the ten commandments, a wife is also listed among the properties of a man (a woman was considered first to be the property of her father, and after marriage her husband). In some verses in the bible the Hebrew words that describe a married woman, or a wife, literally mean “woman with a master.”3
So a woman became the property of a man upon “marrying” him, and was sold by her father in a way comparable to slavery. The future owner of such a woman would have to pay her father the price he requested for his daughter and a contract was made detailing the terms of the transaction.4 This is where the traditions we still have today in certain cultures around the world come from, where the parents of the bride are given money and presents in return for their daughter. These traditions are simply the remnants of the original sales transactions of antiquity, where the daughter was sold to her new owner or husband." https://blog.kareldonk.com/why-getting-married-is-a-very-bad...