Mike L made a similar point in his _Beyond Capital: Marx's Political
Economy of the Working Class_ (NY, St. Martin's, 1992, pp. 112-116). I'd
be interested in hearing what you and others think about that section of
Mike's book.
On the other hand, Marx suggested elsewhere that marriage comes to take
the form of a commodity exchange. Thus, in the _Economic and Philosophic
Manuscripts_, he wrote (provocatively!) that "marriage is a legalized
form of prostitution".
In solidarity, Jerry
PS: since you are teaching a class on labour economics, you might want to
talk to Gil. He is co-authoring a textbook on that subject.