I think both of them are kind of ambivalent on the matter.
Just from the observation of the libertarians Ive met..they just want to smoke pot and screw what ever they feel like at any given moment...not much depth of thought beyond that...
As a libertarian I feel that marriage is a religious sacriment that the state has no busness butting into.
That said:
No Christian should get a “Marriage License” from a state, especially if such licenses are also provided to homosexuals - however - what perverts do is between themselves and God. If they are not recruiting my children they have every right to walk in Hell with their head held high. I will pray for them and minister to them but I cannot force righteousnes upon them. No Christian pastor or priest should EVER at this point consent to performing a state sanctioned marriage.
Marry couples (A man and a woman) before God. Leave the state out of it.
Marriage should not be a federal issue in anyway. It shouldn’t be a state issue. It is a religious issue. It is a legal contractural issue. If the gov took neutral stance then the political stakes wouldn’t exist.
It shocks people but our government didn’t always control marriage.
Marriage has become government run to enforce social outcomes. Child support, alimony.