This is a strawman argument. No one ever said one size fits all with all families, not even God with the example par excellence The Holy Family. A Righteous Step-Father-protector, The Holy Virgin and the Son of God. Not the norm ever but our model.
But there are moral boundaries for male and female relationships created for a reason and when you play with these boundaries eventually it is going to cause damage usually to the most innocent involved
You just spent 4 paragraphs telling me the way that marriages ought to be so I don’t think I am creating a strawman. I am just saying that some families do things differently and it seems to work out for the family (and even the kids turn out alright!).