Hehe aren’t laws and all ‘institutions’ social constructs, by definition? ;) If economic and legal institutions summarized marriage, then I’d lean toward it being a social construct. But what about religious marriages, marriages for love, secret marriages, pre-law marriages, marriage traditions in all countries globally, some of which don’t have marriage laws, pair-bonding and cohabitation without legal marriage, etc.? I guess I feel like people choose partners and intimacy, regardless of laws, and the book I read convinced me that humans gently tend toward having one partner at a time, but obviously not always, and obviously among a wide distribution of behaviors.