"Maturity," as we normally use that word, is not the proper concept in this dynamic. We are talking about "change," and perhaps the ability to comprehend the need to change.
It could be said that at one time the "need" for marriage was to 1) protect the family property, 2) make a political alliance, 3) provide for one's old age by making sure that someone would take care of you, 4) "alllow" two people to legally or morally have sexual intercourse, or 5) populate the planet.
We rarely saw any other reason for marriage. Companionship? Fellow soldiers. Sex? Prostitutes, concubines or mistresses. Love? Didn't figure in the equation. A "vocation"? Perhaps. A "godly" thing? In theory, not, predominantly, in practice.
This idea that the kind of "marriage" defended here by those who call themselves traditionalists is The One Way to look at marriage just doesn't wash. And the Church "signed off" on morganatic marriages, even ordered that the take place.
But we digress.
As for the topic here: I believe it is relatively simple. There is a process by which ELCA congregations can sever their ties with the ELCA. It should be followed - to the letter. It would appear that Pastor Ruby's congregation did this with some care. I disagree with his reasons for leaving, but it seems they acted properly.