Interesting treatise on definition of marriage
I found it interesting that with the first two daughters, Tevye was intially opposed (first husband too poor, second a wild idealist) but he gave in because he witnessed his daughters' happiness.
But with the third he categorically could not accept because she was marrying a non-Jew. So here you have a situation where in society marriage was not accepted between people of different cultures or religions. Tevye reacted with a fervor that would akin to a same-sex marriage of today.
Of course the idea of people of different cultures or religions is hardly an issue to like 95% of the Western cultures, so I take solace that history will ultimately validate and legalized marriage equality will become a reality sooner than we think.
And anyone that postulates "what's next, children or even animals" let me remind you that "civil" marriage is fundametally a "contract" that requires implied consent which children or beasts to not possess.