Good Lord man, do what you want, you don’t have to have a legal marriage, you didn’t in 1780, or 1880, or 1980, or today.
If you don’t care if your marriage is legal, then don’t go through the process to make it so.
Nobody forces people to do that.
The question is why are you so all fired up to have your spousal relationship sanctioned by the state? Don’t you see that by doing so you’ll be allowing it to be equated to a relationship between Bob and Tom or Jane and Lucy.