Really depends on how detailed you want to get. All of the changing marriage systems still involve a single man and single woman, joined in a ceremony, ostensibly sexually and emotionally true to each other, jointly responsible for the production and raising of children, and expected to be in this relationship for the long term. They are similar enough to be recognizable in common language as a "traditional" thing. 

They have more in common than they have with a single mother, live-in boyfriend and girlfriend, and various other current substitutes. Oddly enough, the modern concept of gay marriage comes pretty close.

A modern civic has little in common with a Model-T, but they are still both recognizable as "traditional" cars when compared to a motor bike, a train, or even a volt.

It's an important point to note that the details of our traditional marriage have changed over time, and that conservatives need to be more specific in what they are calling for when they say they value one - but it seems like you're arguing around the point that Ryan was trying to make rather than at it.

Your description of "patriarchal marriage" is almost as distorted and historically inaccurate as Ryan's claims. As early as late antiquity (possibly earlier, but I'm not an expert) there are texts that stress romantic love as a motivating factor in marriage. Certainly by the middle ages and the Renaissance in Europe there's a strong cultural presence of the idea of romantic love, which although not always conjoined with marriage (e.g. the troubadour celebration of love outside marriage), sometimes was. Romantic love wasn't usually seen as the only important factor in a marriage--money and other practical considerations came into it for most people, but them, they still do--but it had a meaningful and acknowledged cultural place.

Moreover, most people chose their own partners. Arranged marriage in Europe was primarily a practice of the landowning aristocracy, a tiny minority of people. And even when marriages were arranged, it was usually with the consent of both parties to be married. The image of the girl sold away by her father to a miserable marriage is much more common as a literary stereotype than as something that actually happened. Nor were women "property" in post-antiquity, premodern European marriages, although they often lacked independent legal status and certainly had far fewer rights than their husbands. Nevertheless, the word "property," is simply incorrect and falsely conflates the injustices of patriarchal marriage with actual slavery. And, notably, married women's loss of rights continued on long after loving companionate marriage became the cultural norm.

Claims such as Ryan's need to be shown as historically false and ethically illegitimate. But nothing is gained if the counterarguments are themselves careless of the truth.

Anyone who says that marriage is or is not something specific is incorrect.

Marriage is.  That is all that can be said.

What I don't understand is this idea that if something is "traditional" that it is somehow better and should be preserved. Slavery, women not being able to vote, 8 year olds working in factories/the fields could all be said to be traditional since they have been happening since the begining of recorded history. Our ideas changed about those thing and I don't see the difference with marriage, things change.

It seems absurd to claim to know what marriage meant or was for given that the origins of officialized pair bonding are lost in pre-history.

Here's a basic description of what takes place in marriages around the world:Marriages, which may involve two people (sometimes one man and one woman, sometimes one person who, regardless of biological sex, behaves as a man in that culture, and one who, regardless of biological sex, behaves as a woman does in that culture) or more than two people (most often one man and multiple women, if he can afford it, and, rarely, one woman and multiple men), take place IN ALL CULTURES for the purposes of raising children and enhancing the survival chances of all concerned, given that economic cooperation does that, and given that economic cooperation between the genders is necessary because every known human society has organized economic activities according to gender, even though what those activities are varies greatly, and even though the things the genders are assumed able to do well also vary greatly.  While married, husbands and wives (however many, and whatever biological sexes they may be) are expected to be publicly faithful to each other in the sense that they owe each other and their children the work of their hands and their bodies for reproductive purposes. If a man has other sex partners on the side, he still must "support" his WIFE/s and their children with his labor. If he shares any of his surplus with other non-wife women, it must be out of his SURPLUS, since he FIRST must give his primary productive capacity to the RECOGNIZED mother of his children. If a woman has other sex partners, she still owes the work of HER hands to her recognized family, which includes her husband and children. And she owes her husband children, or at least the attempt to make them.
Many societies organize families BEYOND marriage,and the extended family is centrally important in everyone's lives. But marriage of SOME form is virtually universal,and it revolves around survival and raising children.
The "traditional marriage" or "traditional family" phrases have no meaning, as they depend on where and when you are standing when you say it. But, as Yrro said, "[all of the various systems of marriage] have more in common than they have with a single mother, live-in
boyfriend and girlfriend, and various other current substitutes. Oddly
enough, the modern concept of gay marriage comes pretty close." The thing that is missing in most other ways of organizing people's love lives, parenting lives, or economic lives, is that they are less stable than marriage WAS in most societies (today in the West, even marriages are unstable). In those societies that allowed divorce, it was allowed because the extended family was strong and was assumed to play a strong role in raising one's children. Our society has become one where individuals think nothing of raising children in unstable arrangements, which research shows are detrimental to children in many ways, and those individuals tell themselves that "children are resilient, they'll be fine." Family systems and marriage systems exist/ed to provide stable environments for the raising of children. Today, as having and raising children take a back seat to adults' personal happiness and fulfillment, adults form temporary liaisons of various sorts, which are fine for the adult, but not so fine if they have a child. Those good old American values of "life, liberty and the pursuit of happiness" actually destroyed marriage by weakening it and replacing stability with "romantic love" as the reason for marrying and staying married. Unfortunately, romantic love turns out to be tremendously unstable. The 20th century version of marriage that politicians praise is actually the version that ended up with the high divorce rate.

 what about entrepreneurship as a universal human value? (also in this clip)