In the spirit of Kevin V.s post, heres a sampling of left-libertarian opinion on the Obergefell ruling:
Sheldon Richman: The Libertarian Case for Legalizing Same-Sex Marriage
Joe Szymanski: The Goal is Free Love
Thomas L. Knapp: Life After Obergefell: Survival Tips for the Dismayed
As a bonus, heres a related left-libertarian piece from a few months earlier:
James C. Wilson : Same-Sex Marriage is Not Enough: Separate Marriage and State
And finally, a piece of mine from a few years back on the definitional question: Victory Through Lexicography?