Taking god out of the issue (which always seems a good idea to me), and looking at marriage as useful function of society, the issue is almost a moot one.
And therefore is entirely political.

The function of a family unit is the strongest, most stable, most psychologically healthy -for rearing offspring.
Marriage - as a tool of society - to maintain it's stable breeding stock - is a very good one.
One that, (without god interfering), appears to have been a basic human instinct as the most efficient way to achieve the optimum procreation quality.

I think this disruption to a 'natural order' of things is unhelpful to society as a whole. More than unhelpful, detrimental.

Leaving aside an adults (childish) need for confirmation of a societies approval, this is just another example of cultural marxism getting in the way of commonsense, and pushing for the breakdown of families.

Families being the main target of destruction.
Without the family being destroyed, the pushing of socialism, and all its evils, is doomed to failure.
(it is anyway, but hey. )