Well then you have to get government out of tax issues (or get rid of the IRS as te same time) becuase the priary reason that government is in the business of recognizing marriage is for Taxes/tax filings.
It isn’t just government that recognized marriages. If your employer gives medical benefits, your spouse also is elligible.
However many firms also offer benefits for unmarried domestic partners (at least of same sex couples).
I've got no problem with that. We, as citizens, are not obligated to live our lives solely to satisfy the requirements of the IRS.
However, I am NOT suggesting that a marital partnership requires "no legal recognition". I am saying, it shouldn't be the basis for defining "marriage".