You're talking about involuntary, yes?
You're not saying that a couple must be deemed unfit before they can
voluntarily give guardianship?
That is what the judge (senior judge in the county) said in open court during a proceeding in which I was pursuing guardianship. Child's mother was present and had provided notarized consent. Child's father was imprisoned with at least 4 years remaining, and had not provided consent but was not contesting the matter. The word "unfit" was not used, but that was definitely the idea. To paraphrase as closely as my memory will allow:
"You do understand that in order to grant this guardianship, I must rule that you yourself are incapable of raising your child."
Mom balked at that criteria, and though she was ready to hand her child over to me so she could go carry on with her carefree party life, she wouldn't stand for anyone judging her mothering skills. She wouldn't go so far as to revoke her consent, but waffled on the issue enough that the judge gave us a 90-day continuance to think about it. I had the case dismissed when Mom left the child with his paternal grandmother and disappeared to parts unknown.